Desulfurization slurry waste heat recovery system

Abstract

The present application relates to the field of energy saving and environmental protection and flue gas desulfurization waste heat utilization, in particular to a desulfurization slurry waste heat recovery system, the system comprises: a desulfurization tower, a slurry pipe, a slurry heat exchanger, a heat supplement device and a warm air device, further comprising a heat medium flow adjusting device, the heat supplement device is used to supplement heat for the heat medium flowing between the slurry heat exchanger and the warm air device, and the heat medium flow adjusting device is used to adjust the flow of the heat medium, so that the problems of poor system reliability, complex system structure, poor environmental adaptability, low waste heat utilization rate and low investment return rate of the desulfurization slurry waste heat recovery system in use are ingeniously solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of energy saving and environmental protection and flue gas desulfurization waste heat utilization, and particularly relates to a desulfurization slurry waste heat recovery system. BACKGROUND

[0002] The large-scale application of coal power provides energy guarantee for economic and social development, but also poses challenges to energy saving and emission reduction and environmental governance.

[0003] In order to reduce environmental pollution caused by coal combustion, flue gas emission treatment needs to be performed on the coal-fired boiler. The most common flue gas treatment process is the limestone-gypsum wet desulfurization process. The basic principle of the limestone-gypsum wet desulfurization process is that high-temperature original flue gas at 120-150℃ enters a desulfurization tower and is in counter contact with the absorbent (i.e. desulfurization slurry) sprayed downward. After the original flue gas is washed by the absorbent, the sulfur-containing gas in the flue gas is removed, and the flue gas temperature is reduced to about 50℃, and then the flue gas is discharged through a chimney. In the flue gas treatment process, most of the waste heat in the flue gas is exchanged in the contact with the desulfurization slurry. The water in the slurry is vaporized into the flue gas, the flue gas temperature is reduced, and the water vapor is increased. Finally, they are discharged into the atmosphere together. The flue gas waste heat is not effectively recovered and utilized, and in order to improve the desulfurization efficiency and reduce pollutant emissions, a process system for cooling the desulfurization slurry is often used in the wet flue gas desulfurization process, which further causes multiple energy waste. How to effectively recover the waste heat of flue gas has become a problem to be solved in the field.

[0004] In practice, various forms of exploration have been carried out on the waste heat utilization of the wet flue gas desulfurization slurry. The waste heat utilization technology can be divided into the following ways: (1) using heat exchange technology to take out the waste heat in the slurry through heat exchange and supply it to the demand end; (2) using liquid-solid separation technology to take out the waste heat in the liquid phase and supply it to the demand end; (3) using flash evaporation technology to flash evaporate the water in the slurry into steam and supply it to the demand end; (4) using heat pump technology to take out the waste heat in the slurry and supply it to the demand end. Among them, the heat exchange technology has been applied due to its simple process route. However, due to the influence of various factors, the efficiency of waste heat utilization is not ideal. The main technical problems are as follows: (1) the desulfurization slurry contains gypsum and other particulate matters, which may cause safety hidden trouble problems such as blockage, wear and corrosion of the equipment in the waste heat recovery system; (2) the heat balance problem of the desulfurization slurry waste heat recovery system; (3) the water balance problem of the desulfurization slurry system.

[0005] To solve the above problems, CN21043429U discloses a system for recovering waste heat of slurry by using slurry heat exchanger, which adopts a non-contact straight channel slurry heat exchanger structure to solve the problems of slurry blockage, heat transfer efficiency, pressure drop, etc. The clean flue gas after desulfurization and cooling is discharged through the chimney. The warm air heater utilizes the waste heat of the desulfurization slurry to heat air, etc., which not only recovers the waste heat of the desulfurization slurry, but also has the advantages of simple system and small occupied area. However, this patent still has some technical problems that need to be improved:

[0006] (1) During the flue gas desulfurization process, the flue gas temperature and the moisture content of the flue gas are often dynamically changing. Changes in factors such as flue gas temperature and moisture content can cause fluctuations in the amount of slurry waste heat recovered, which in turn can cause unstable air temperature rise when the air is preheated by the warm air heater, and there may be cases where the air temperature rise does not meet the design value.

[0007] (2) In order to meet the application requirements of the entire winter season, the slurry waste heat recovery system is usually designed according to the maximum heat load required by the warm air heater in the extremely cold period to meet the requirements of the warm air heater in the extremely cold period. Excessive recovery of waste heat from the slurry can cause excessive condensate to condense from the flue gas. When this condensate enters the desulfurization tower, it can cause the liquid level in the desulfurization tower to be unable to maintain within a certain range, disrupting the water balance of the desulfurization tower system. Conversely, without disrupting the water balance of the desulfurization tower system, the amount of waste heat recovered from the slurry is usually insufficient to meet the heat demand of the warm air heater in the winter extremely cold period. Therefore, the original patent has the problem of mismatch between the slurry waste heat recovery heat load in the extremely cold period and the heat load required by the warm air heater.

[0008] (3) Based on point (2), if the slurry waste heat recovery system equipment is configured according to the requirements of the warm air heater in the extremely cold period, and due to the fact that the heat load required in the early and late winter cold periods is only 20% to 50% of the heat load required in the extremely cold period, and the number of days in the extremely cold period is relatively small, this can cause the entire system to operate at low load for a long time, resulting in a situation where "a horse is pulling a cart". The recovered waste heat cannot be fully utilized, and the waste heat utilization rate is low.

[0009] (4) The slurry waste heat recovery system disclosed in the patent can only meet the heating requirements of the primary air warm air heater or the secondary air warm air heater in the winter extremely cold period, and cannot simultaneously meet the heating requirements of both the primary air warm air heater and the secondary air warm air heater. In order to ensure the heating requirements of the primary warm air heater and the secondary warm air heater, a conventional steam warm air system still needs to be retained, resulting in the coexistence of the waste heat warm air heater system and the conventional steam warm air system, which complicates the system structure. At the same time, most of the recovered slurry waste heat is not utilized in the early and late winter cold periods, resulting in a low waste heat utilization rate, a long payback period, and low implementability.

[0010] Therefore, how to further optimize the process route of the desulfurization slurry waste heat recovery system, without destroying the water balance of the desulfurization tower and fully utilizing the waste heat of the slurry, improving the investment return, and the system is simple and highly implementable, is still a problem of great concern in the field. SUMMARY

[0011] The purpose of the present application is to provide an optimized desulfurization slurry waste heat recovery system, which is additionally provided with a heat supplement device (heat supplement system), and the system can further include a heat medium flow adjusting device.

[0012] To solve the above technical problems, the technical scheme provided by the present application is as follows:

[0013] A desulfurization slurry waste heat recovery system, characterized in that the system comprises a desulfurization tower, a plurality of slurry pipes, a slurry heat exchanger, a heat supplement device and a warm air device, wherein:

[0014] The bottom of the desulfurization tower is provided with a slurry pool, and the upper part of the desulfurization tower is provided with a plurality of layers of spray pipes; the spray pipes are connected in sequence with the slurry pool through a plurality of slurry pipes;

[0015] The slurry heat exchanger is arranged on part of the pipelines or all of the pipelines of the plurality of spray pipes, and the slurry heat exchanger comprises a slurry flow channel and a heat medium flow channel in heat exchange with the slurry flow channel;

[0016] The warm air device comprises a heat medium flow channel and an air medium flow channel in heat exchange with the heat medium flow channel;

[0017] The heat medium flow channel of the slurry heat exchanger and the heat medium flow channel of the warm air device are connected through a heat medium pipeline to realize the circulation flow of the heat medium between the warm air device and the slurry heat exchanger;

[0018] A heat supplement device is arranged on the heat medium pipeline between the slurry heat exchanger and the warm air device to supplement heat for the heat medium circulating between the slurry heat exchanger and the warm air device.

[0019] Optionally, a slurry heat exchanger is arranged on the slurry pipe connected with the top layer, the second top layer and / or the third layer of the plurality of layers of spray pipes. Optionally, a slurry heat exchanger is arranged on the slurry pipe connected with the top layer and the second top layer of the plurality of layers of spray pipes, respectively. Further optionally, a slurry heat exchanger is arranged on the slurry pipe connected with the top layer of the plurality of layers of spray pipes.

[0020] Preferably, the slurry heat exchanger is arranged on the vertical pipe section of the slurry pipe.

[0021] Preferably, the slurry heat exchanger is a fully-welded plate heat exchanger.

[0022] Further preferably, the slurry heat exchanger is a fully-welded plate heat exchanger with straight channel structure. The heat transfer element used is corrugated plate, and each two corrugated plates are coupled to form a plate pair, and multiple plate pairs are stacked to form a plate bundle, and slurry flow channels and heat medium flow channels are alternately formed on both sides of the plate bundle, the two plates in the slurry flow channel have corrugations protruding to the slurry flow channel side, and the sum of the heights of the protruding corrugations is less than the distance between the slurry flow channels; the slurry inlet reducer, the slurry flow channels of the plate bundle, and the slurry outlet reducer of the straight channel slurry heat exchanger are substantially on the same axis as the flow direction of the slurry.

[0023] Optionally, the air heater is one set for heating the primary air and / or the secondary air. Further optionally, the air heater is two sets including a first air heater and a second air heater for heating the primary air and the secondary air, respectively. In actual application, each set of air heater can be one device or multiple devices.

[0024] Preferably, the air heater is a fully-welded plate heat exchanger.

[0025] Optionally, a heat medium supplementing device is further provided on the heat medium pipeline to maintain the stability of the heat medium system. The present application does not have special limitations on the heat medium supplementing device, as long as it can achieve the function of supplementing heat medium. The heat medium supplementing device can be a closed heat medium supplementing device or an open heat medium supplementing device. Common closed heat medium supplementing devices include expansion tanks, high-level tanks, or heat medium supplementing pumps, etc. The open heat medium supplementing device refers to a heat medium tank in communication with the atmosphere.

[0026] A heat supplementing device is provided on the heat medium pipeline between the slurry heat exchanger and the air heater, which supplements heat to the heat medium flowing between the slurry heat exchanger and the air heater by using a high-temperature heat source to meet the heat demand of the air heater.

[0027] The present application does not have special limitations on the heat supplementing device, as long as it can supplement heat to the heat medium flowing between the slurry heat exchanger and the air heater. The heat supplementing device can be a conventional tubular or plate heat exchanger, or an open heat supplementing device, which refers to a heat medium supplementing tank in communication with the atmosphere. The high-temperature heat source is a common heat-conducting medium, such as high-temperature steam or hot water, etc.

[0028] The working principle of the heat supplementing device in the desulfurization slurry waste heat recovery system is as follows:

[0029] The heat medium of the slurry heat exchanger absorbs heat from the desulfurization slurry and the temperature rises, and the heated heat medium flows into the heat supplementing device through the heat medium pipeline;

[0030] According to the temperature of the cold air flowing into the air heater and the heat load demand, it is judged whether the heat medium needs to be heated by the heat supplement device. If the heat load demanded by the air heater is greater than the heat load recovered by the slurry heat exchanger, the heat supplement device is started to heat the heat medium, and the heat load demand of the air heater is met through the heat supplement device.

[0031] The heat medium flows into the air heater after passing through the heat supplement device, and exchanges heat with the cold air flowing through the air heater. The air temperature rises and enters the air preheater, and the heat medium after heat exchange is lowered in temperature and flows into the slurry heat exchanger again.

[0032] Optionally, a heat medium flow adjusting device is arranged on the heat medium pipeline of the slurry waste heat recovery system to adjust the flow of the heat medium in the slurry heat exchanger and / or the air heater.

[0033] The heat medium flow adjusting device is not particularly limited in the present application. Common heat medium flow adjusting devices include heat medium bypasses and / or heat medium pumps and / or valves. The heat medium bypasses can be pipelines, valves between the heat medium inlet and outlet of the slurry heat exchanger, and / or pipelines, valves between the heat medium inlet and outlet of the air heater, and / or pipelines, valves between the heat medium inlet and outlet of the heat medium pump. The heat medium pump can be a variable frequency pump.

[0034] The working principle of the heat medium flow adjusting device in the desulfurization slurry waste heat recovery system is as follows:

[0035] The heat medium of the slurry heat exchanger absorbs heat from the desulfurization slurry and the temperature rises. If the heat load demanded by the air heater is less than the heat load recovered by the slurry heat exchanger, the heat medium flow adjusting device is started to adjust the flow of the heat medium, reduce the flow of the heat medium in the slurry heat exchanger and / or the air heater, and then meet the heat load demand of the air heater.

[0036] The present application has the following advantages:

[0037] (1) The heat medium flowing between the slurry heat exchanger and the air heater is heated by the heat supplement device, which ingeniously solves the problem of unstable air temperature rise in the air heater caused by fluctuations in the temperature of the flue gas and the moisture content of the slurry, and improves the reliability of the air heater system.

[0038] (2) through the heat supplement system to adjust the peak heat, to meet the needs of a set of heating equipment for primary air, secondary air heating, the system structure is simple; in the premise of maintaining the desulfurization tower system water balance, the maximum recovery and utilization of slurry waste heat, save steam to reduce coal consumption, deducting its own operating energy consumption, conversion of standard coal, power generation coal consumption is reduced by 1.5~4.5g / KW·h (conversion of annual power generation), compared with no heat supplement process, energy saving effect is improved by 20%~45%;

[0039] (3) using the heat supplement device and the heat medium flow adjusting device to control the slurry waste heat recovery heat load, can realize the connection control with the desulfurization system, according to the liquid level of the desulfurization tower, dynamically adjust the slurry waste heat recovery heat load of the slurry waste heat recovery system, can effectively avoid the excessive slurry waste heat recovery heat load due to the large demand heat load of the warm air heater in the extremely cold period, too much flue gas condensate in the desulfurization tower, destroy the water balance of the desulfurization system, realize the control of the water balance of the desulfurization system. Control the recovery of slurry waste heat, and the appropriate flue gas condensate enters the desulfurization tower, and the water consumption of the desulfurization tower can be reduced by 30%~60%, and the water resource saving effect is remarkable;

[0040] (4) due to the warm air heater system required heat load in the early and late cold period is only 20%~50% of the heat load required in the extremely cold period, the required heat load changes greatly; after adding the heat supplement system, the system operation flexibility is high, and it is fully suitable for the operation requirement of the large change of the warm air heater heat load. In the early and late cold period, the slurry waste heat is fully utilized, and the heat load demand is appropriately supplemented in the extremely cold period. The waste heat utilization rate is greatly improved, and the environmental adaptability is strong. The "big horse pulling small cart" working condition can be avoided, and the system can be well applied to the condition that the environmental temperature difference between the extremely cold period and the early and late cold period is large;

[0041] (5) in the early and late cold period of winter, the warm air heater heat load demand is small, the heat medium flow adjusting device is used to adjust the heat medium flow in the slurry heat exchanger and / or the warm air heater, and the slurry heat exchanger waste heat recovery amount is reduced, so as to adapt to the low load operation condition of the warm air heater;

[0042] (6) compared with the non-heat supplement process, the system investment of the system design of the present application increases by 10%~15%, and the annual recovery benefit is improved by 20%~45%, thereby greatly reducing the investment recovery period;

[0043] (7) the straight channel full-welded plate heat exchanger is adopted, so that the blockage is avoided, and the land occupation area and energy consumption are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 : a desulfurization slurry waste heat recovery system schematic diagram shown in embodiment 1 of the present application

[0045] Figure 2 : a desulfurization slurry waste heat recovery system schematic diagram shown in embodiment 2 of the present application

[0046] Figure 3 Figure 3 shows a schematic diagram of a desulfurization slurry waste heat recovery system according to an embodiment of the present application

[0047] Figure 4 Figure 4 shows a schematic diagram of a desulfurization slurry waste heat recovery system according to an embodiment of the present application

[0048] Figure 5 Figure 5 shows a schematic diagram of a flow channel cross section of a slurry heat exchanger according to the present application

[0049] Figure 6 Figure 6 shows a schematic diagram of a corrugated sheet structure of a slurry heat exchanger according to the present application

[0050] Figure 7 Figure 7 shows a schematic diagram of a structure of a slurry heat exchanger according to the present application

[0051] Figure 8 Figure 5 shows a schematic diagram of a desulfurization slurry waste heat recovery system according to an embodiment of the present application

[0052] Figure 9 Figure 6 shows a schematic diagram of a desulfurization slurry waste heat recovery system according to an embodiment of the present application

[0053] BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Desulfurization tower 1; slurry pool 101; spray pipe 102; slurry pipe 2; slurry heat exchanger 3; heat supplement device 4; warm air device 5; first warm air device 51; second warm air device 52; raw flue gas A; clean flue gas B; desulfurization slurry M; heat medium N; high-temperature heat source E; primary air F; secondary air G; corrugated sheet 7; support corrugation 701; pressure-bearing corrugation 702; heat transfer corrugation 703; plate bundle 301; inlet size head 303; outlet size head 302; vertical pipe section 201; slurry flow channel C; heat medium flow channel D; heat medium pump 8; heat medium supplement device 9; heat medium bypass 10; valve 11. DETAILED DESCRIPTION

[0055] The present application will now be further described with reference to the accompanying drawings, but the following embodiments do not constitute a limitation on the present application.

[0056] Embodiment 1

[0057] Figure 1 A desulfurization slurry waste heat recovery system according to the present application is shown, which comprises a desulfurization tower 1, a plurality of slurry pipes 2, a slurry heat exchanger 3, a heat supplement device 4, and a warm air device 5, wherein,

[0058] The desulfurization tower 1 is provided at the bottom with a slurry pool 101, and the upper part of the desulfurization tower is provided with a plurality of spray pipes 102; the plurality of spray pipes 102 are connected in sequence with the slurry pool 101 through the plurality of slurry pipes 2.

[0059] A slurry heat exchanger 3 is arranged on the slurry pipe 2 connected with the topmost layer and the second top layer of the spray pipe 102 respectively; the slurry heat exchanger 3 has a slurry flow channel and a heat medium flow channel in heat exchange with the slurry flow channel.

[0060] Preferably, the slurry heat exchanger is arranged on the vertical pipe section of the slurry pipe 2.

[0061] Preferably, the slurry heat exchanger 3 is a full-welded plate heat exchanger, and the full-welded plate heat exchanger disclosed in the patent CN210434297U is suitable for the present application. Specifically, the slurry heat exchanger 3 is a full-welded plate heat exchanger with straight channel structure, and the specific structure is shown in Figures 5-7 .

[0062] As shown in Figure 5 , Figure 6 , the heat transfer element in the slurry heat exchanger 3 is a corrugated plate 7, which includes equidistantly protruding support corrugations 701, lower concave pressure-bearing corrugations 702, and protruding heat transfer corrugations 703. The corrugated plates 7 are arranged in pairs to form plate pairs. The slurry flow channel C and the heat medium flow channel D are formed on both sides of the corrugated plates. The lower concave pressure-bearing corrugations form contact points in the heat medium flow channel. The sum of the heights of the protruding support corrugations is equal to the height of the slurry flow channel. The protruding heat transfer corrugations protrude into the slurry flow channel. The sum of the protruding heights of the corrugations on both sides of the slurry flow channel, i.e., the sum of the protruding height H2 of the corrugations on one side of the slurry flow channel and the protruding height H3 of the corrugations on the other side of the slurry flow channel, is less than the height H1 of the slurry flow channel, i.e., H1 > H2 + H3. Correspondingly, the heat transfer corrugations in the slurry flow channel cannot form contact points, i.e., the desulfurization slurry flows in the channel without contact points, which solves the problem of stagnation points in the flow field of the tubular and conventional plate heat exchangers. The particles in the desulfurization slurry are less likely to accumulate, thereby solving the problem of blockage. At the same time, since the heat transfer element is a corrugated plate, compared with the tubular slurry heat exchanger, the heat transfer efficiency is high, the cold end temperature difference is small, and under the same cold source conditions, the outlet temperature of the desulfurization slurry is lower.

[0063] Further, referring to Figure 7 , a plurality of plate pairs composed of corrugated plates 7 are stacked to form a plate bundle 301. The inlet and outlet ends of the plate bundle 301 are connected to the inlet size head 303 and the outlet size head 302 respectively. The flow direction of the desulfurization slurry is basically on the same axis and basically coincides with the central axis of the vertical pipe section 201 of the slurry pipeline, thereby further reducing the probability of blockage of the slurry flow channel by the desulfurization slurry.

[0064] It should be noted that Figures 5-7 only one structure of the slurry heat exchanger structure is shown, and other slurry heat exchangers 3 with straight channel structure are also within the protection scope of the present patent.

[0065] The air heater 5 has a heat medium flow channel and an air medium flow channel which exchanges heat with the heat medium flow channel, Figure 1 The air heater 5 is two sets, including a first air heater 51 and a second air heater 52, which are respectively used for heating the primary air F and the secondary air G, and the heated air enters the air preheater. Alternatively, the air heater can also be one set for heating the primary air and / or the secondary air. In actual application, each set of air heater can be one device or multiple devices.

[0066] The heat medium flow channel of the slurry heat exchanger 3 is connected with the heat medium flow channel of the air heater 5 through a heat medium pipeline, so as to realize the circulation of the heat medium between the air heater and the slurry heat exchanger.

[0067] Preferably, the air heater 5 adopts a fully-welded plate heat exchanger, which solves the problems of large volume and large floor area of the conventional heat exchanger by using the compact and efficient characteristics of the plate heat exchanger.

[0068] A heat compensator 4 is arranged on the heat medium pipeline between the slurry heat exchanger 3 and the air heater 5, and the heat compensator 4 compensates the heat of the heat medium circulating between the slurry heat exchanger 3 and the air heater 5 through a high-temperature heat source E, so as to meet the heat demand of the air heater.

[0069] The heat compensator 4 is not particularly limited in the application, as long as it can compensate the heat of the heat medium circulating between the slurry heat exchanger and the air heater. Preferably, the heat compensator is a tube heat exchanger or a plate heat exchanger, and the heat compensator can also be an open heat compensation device, which is a heat medium compensation tank in communication with the atmosphere. The high-temperature heat source E is a common heat-conducting medium, such as high-temperature steam or hot water.

[0070] The basic principle of the desulfurization slurry waste heat recovery system is as follows:

[0071] The heat medium of the slurry heat exchanger absorbs heat from the desulfurization slurry and is heated, and the heated heat medium flows into the heat compensator through the heat medium pipeline;

[0072] According to the temperature of the cold air entering the air heater and the heat load demand, it is determined whether the heat medium needs to be heated through the heat compensator; if the heat medium needs to be heated, the heat compensator is started to adjust the temperature of the heat medium, so as to meet the heat exchange demand of the air heater;

[0073] The heat medium flows into the air heater after passing through the heat compensator, and exchanges heat with the cold air flowing through the air heater, and the heated air enters the air preheater, and the heat-exchanged heat medium is cooled and enters the slurry heat exchanger again.

[0074] Example 2

[0075] Figure 2 Another desulfurization slurry waste heat recovery system of the present application is shown. Compared with the embodiment 1, the difference between the two is that in the embodiment 2, only one slurry heat exchanger 3 is arranged on the slurry pipe 2 connected with the top layer of the spray pipe 102, and other structures are the same as the embodiment 1.

[0076] Embodiment 3

[0077] Figure 3 Another desulfurization slurry waste heat recovery system of the present application is shown. Compared with the embodiment 2, the difference between the two is that in the embodiment 3, only one air heater 5 is arranged for heating the primary air and / or the secondary air. Other structures are the same as the embodiment 2.

[0078] Embodiment 4

[0079] Figure 4 Another desulfurization slurry waste heat recovery system of the present application is shown. Compared with the embodiment 1, the difference between the two is that in the embodiment 4, only one air heater 5 is arranged for heating the primary air and / or the secondary air.

[0080] Embodiment 5

[0081] Figure 8 Another desulfurization slurry waste heat recovery system of the present application is shown. Compared with the embodiment 1, the difference between the two is that a heat medium supplement device 9 is arranged on the heat medium pipeline to maintain the stability of the heat medium system.

[0082] The heat medium supplement device 9 is not particularly limited in the present application, as long as it can achieve the function of supplementing the heat medium. The heat medium supplement device 9 can be a closed heat medium supplement device or an open heat medium supplement device. Common closed heat medium supplement devices include expansion tanks, high-level tanks or heat medium supplement pumps, etc. The open heat medium supplement device refers to a heat medium tank in communication with the atmosphere.

[0083] Embodiment 6

[0084] Figure 9 Another desulfurization slurry waste heat recovery system of the present application is shown. Compared with the embodiment 3, the difference between the two is that a heat medium flow regulating device is arranged on the heat medium pipeline, which includes a heat medium bypass 10, a valve 11 and a heat medium pump 8, to regulate the heat medium flow, so as to regulate the heat medium flow in the slurry heat exchanger and / or the air heater. If the heat load required by the air heater is less than the heat load recovered by the slurry heat exchanger, the heat medium flow regulating device can be opened to regulate the heat medium flow, reduce the heat medium flow in the slurry heat exchanger and / or the air heater, and meet the requirement of the air heater.

[0085] It is particularly pointed out that the present application does not limit whether the heat medium flow regulating device comprises the heat medium bypass 10, the valve 11 and the heat medium pump 8 simultaneously, and the heat medium flow regulating device arranged in the slurry waste heat recovery system can be the heat medium bypass 10 and / or the valve 11 and / or the heat medium pump 8.

[0086] In addition, although the heat medium flow regulating device is only shown in the embodiment 6, the heat medium flow regulating device is suitable for all the embodiments of the present application.

[0087] The beneficial effects of the embodiments of the present application are as follows:

[0088] (1) The heat medium flowing between the slurry heat exchanger and the air heater is heated by the heat supplement device, which solves the problem that the slurry waste heat recovery amount fluctuates due to factors such as smoke temperature fluctuation and humidity fluctuation of the slurry desulfurization system, and further causes the air temperature rise amplitude of the air heater to be unstable, thereby improving the reliability of the air heater system;

[0089] (2) The peak-shaving heat supplement is performed by the heat supplement system, which realizes that a set of heating equipment simultaneously meets the heating requirements of the primary air and the secondary air, the system structure is simple, the slurry waste heat is maximally recovered and utilized under the premise of maintaining the water balance of the desulfurization tower system, the steam is saved and the coal consumption is reduced, the converted standard coal is deducted, and the power generation coal consumption can be reduced by 1.5-4.5 g / KW·h; compared with the process without heat supplement, the energy saving effect is improved by 20%-45%;

[0090] (3) The slurry waste heat recovery heat load is controlled by using the heat supplement device and the heat medium flow regulating device, which can realize the connection control with the desulfurization system, dynamically adjust the slurry waste heat recovery heat load of the slurry waste heat recovery system according to the liquid level of the desulfurization tower, and effectively avoid the excessive slurry waste heat recovery heat load due to the large demand heat load of the air heater in the extremely cold period, the excessive flue gas condensate in the desulfurization tower, the destruction of the water balance of the desulfurization tower system, and the realization of the control of the water balance of the desulfurization tower system. The control of the recovery of the slurry waste heat, and the appropriate flue gas condensate into the desulfurization tower can reduce the water consumption of the desulfurization by 30%-60%, and the water resource saving effect is remarkable;

[0091] (4) Since the heat load required by the air heater system in the early and late cold periods of winter is only 20%-50% of the heat load required in the extremely cold period, the heat load required by the system changes greatly; after the heat supplement system is added, the system operation flexibility is high, and it fully meets the operation requirements of the large change of the heat load of the air heater. In the early and late cold periods, the slurry waste heat is fully utilized, and in the extremely cold period, appropriate heat supplement is made to meet the heat load requirement, the waste heat utilization rate is greatly improved, the environmental adaptability is strong, the "big horse pulling a small cart" working condition can be avoided, and the system can be well applied to the condition that the environmental temperature difference between the extremely cold period and the early and late cold periods in winter is large;

[0092] (5) In the early and late winter cold period, the warm air heater has small heat load demand, the heat medium flow adjusting device is used to adjust the heat medium flow, the waste heat recovery amount of the slurry heat exchanger is reduced, and the low load operation condition of the warm air heater is adapted;

[0093] (6) Compared with the non-heat supplement process, the system investment of the system is increased by 10%-15%, and the annual recovery benefit is increased by 20%-45%, so that the investment recovery period is greatly reduced;

[0094] (7) The new straight channel all-welded plate heat exchanger is adopted, so that blockage is avoided, and the land occupation area and energy consumption are reduced.

[0095] The desulfurization slurry waste heat recovery system provided by the present application is described in detail, the principle and implementation mode of the present application are described by applying specific examples in the specification, and the above implementation description is only used for helping understanding the present application, and the content of the specification should not be understood as limiting the present application.

Claims

1. A desulfurization slurry waste heat recovery system characterized by, The system comprises: a desulfurization tower, a slurry pipe, a slurry heat exchanger, a heat supplement device and a warm air device, a heat medium supplement device, a heat medium flow regulating device; wherein the bottom of the desulfurization tower is provided with a slurry pool, and the upper part of the desulfurization tower is provided with multiple layers of spray pipes; the spray pipes are connected with the slurry pool in sequence through multiple slurry pipes; the slurry heat exchanger is arranged on part or all of the pipe lines of the spray pipes, and comprises a slurry flow channel and a heat medium flow channel; the warm air device comprises a heat medium flow channel and an air medium flow channel; the heat medium flow channel of the slurry heat exchanger and the heat medium flow channel of the warm air device are connected through a heat medium pipe line to realize the circulation flow of the heat medium between the warm air device and the slurry heat exchanger; a heat supplement device is arranged on the heat medium pipe line between the slurry heat exchanger and the warm air device to supplement the heat of the heat medium circulating between the slurry heat exchanger and the warm air device; a heat medium supplement device and a heat medium flow regulating device are arranged on the heat medium pipe line; the heat medium supplement device is a closed heat medium supplement device or an open heat medium supplement device; the closed heat medium supplement device is an expansion tank, an elevated tank or a heat medium supplement pump; the open heat medium supplement device is a heat medium tank in communication with the atmosphere; the heat supplement device is a pipe heat exchanger, a plate heat exchanger or an open heat supplement device; the open heat supplement device is a heat medium supplement tank in communication with the atmosphere; the heat medium flow regulating device is a heat medium bypass and / or a heat medium pump and / or a valve regulating device; the heat medium bypass is a pipe line, a valve between the heat medium inlet and outlet of the slurry heat exchanger, and / or a pipe line, a valve between the heat medium inlet and outlet of the warm air device, and / or a pipe line, a valve between the inlet and outlet of the heat medium pump.

2. The desulfurized slurry waste heat recovery system according to claim 1, wherein A slurry heat exchanger is arranged on the slurry pipe connected with the top layer, the second top layer and / or the third layer of the multiple layers of spray pipes.

3. The desulfurized slurry waste heat recovery system according to claim 1, wherein A slurry heat exchanger is arranged on the slurry pipe connected with the top layer and the second top layer of the multiple layers of spray pipes.

4. The desulfurized slurry waste heat recovery system according to claim 1, wherein A slurry heat exchanger is arranged on the slurry pipe connected with the top layer of the multiple layers of spray pipes.

5. The desulfurized slurry waste heat recovery system according to any one of claims 2 to 4, characterized by, The slurry heat exchanger is arranged on the vertical pipe section of the slurry pipe.

6. The desulfurized slurry waste heat recovery system according to claim 1, wherein The slurry heat exchanger is a fully-welded plate heat exchanger.

7. The desulfurized slurry waste heat recovery system according to claim 6, wherein The fully-welded plate heat exchanger is a fully-welded plate heat exchanger with straight channel structure.

8. The desulfurized slurry waste heat recovery system according to claim 7, wherein The heat transfer element of the fully-welded plate heat exchanger with straight channel structure is a corrugated plate sheet; every two corrugated plate sheets are oppositely buckled to form a plate pair, multiple plate pairs are stacked to become a plate bundle, and the slurry flow channel and the heat medium flow channel are alternately formed on both sides of the plate sheet; both the plate sheets in the slurry flow channel have corrugations protruding to the side of the slurry flow channel; the sum of the heights of the protruding corrugations is less than the distance between the slurry flow channels; the slurry inlet reducer, the slurry flow channel of the plate bundle and the slurry outlet reducer of the slurry heat exchanger are basically on the same axis with the flow direction of the slurry.

9. The desulfurized slurry waste heat recovery system according to claim 1, wherein The warm air device is a set for heating the primary air and / or the secondary air.

10. The desulfurized slurry waste heat recovery system according to claim 1, wherein The warm air device is two sets including a first warm air device and a second warm air device for heating the primary air and the secondary air respectively.

11. The desulfurized slurry waste heat recovery system according to claim 1, wherein The warm air device is a fully-welded plate heat exchanger.

12. The desulfurized slurry waste heat recovery system according to claim 1, wherein The heat medium pump is a variable frequency pump. The heat medium pump is a variable frequency pump.

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