A control method for paper drying energy supply coupling system

Abstract

A control method for a papermaking drying energy supply coupling system, wherein the gas turbine power generation of the system is used to solve the power demand of the paper mill or to access the Internet, and the generated flue gas partially enters the paper machine hood for drying, and partially enters the high- and low-pressure boiler to generate steam, and can then enter the high- and low-pressure separators to adjust the steam parameters to generate the required various types of steam, and the generated steam partially enters the paper machine dryer for drying, and the other steam can be used for other processes or sold to surrounding heat users, and the flue gas coming out of the boiler enters the heat exchanger or lithium bromide unit to solve the heating or cooling needs of the park, and if the flue gas generated by the gas turbine does not meet the flue gas or steam needs of the paper machine, the corresponding supplementary combustion equipment can be started, and the control method optimizes and controls the energy supply process according to different energy requirements. The present invention can solve various energy requirements of different working conditions of the paper mill in a low-carbon, clean and efficient manner, and has high flexibility, strong practicality and good matching.

Description

Technical Field

[0001] The invention relates to a control method for a papermaking drying energy supply coupling system. Background Art

[0002] The papermaking industry is an important basic raw material industry for national economic and social development, and it is also a high-energy-consuming and high-polluting industry. In this context, the development of the papermaking industry faces huge challenges. How to achieve clean, efficient and low-carbon production has become a difficult problem that the papermaking industry must solve.

[0003] Paper drying is the most energy-intensive process in the papermaking process. How to effectively reduce the energy consumption of drying and achieve clean, efficient and low-carbon energy supply is the key to the breakthrough development of the papermaking industry.

[0004] At present, paper mills require a variety of energy for paper drying, including electricity, heat and steam. Electricity is mainly purchased from the power grid, steam is mainly provided by coal-fired boilers, and heat is mainly provided by gas and oil equipment. Therefore, the energy supply equipment is scattered, with low energy efficiency and high energy costs. Summary of the invention

[0005] In order to solve the above technical problems, the present application proposes a control method for a papermaking drying energy supply coupling system.

[0006] In the first aspect, the present invention proposes a paper drying energy supply coupling system for the above-mentioned technical problems, including a gas turbine, and a high-pressure steam boiler, a high-pressure separator, a low-pressure steam boiler, a low-pressure separator, a left afterburner, a right afterburner, a first fresh air fan, a second fresh air fan, a first air hood outlet exhaust fan, a second air hood outlet exhaust fan, a lithium bromide unit, a heat exchanger, a condenser, a deaerator, a first high-pressure boiler feed pump, a second high-pressure boiler feed pump, a first low-pressure boiler feed pump, and a second low-pressure boiler feed pump connected to the gas turbine.

[0007] In a second aspect, the present invention provides a control method for a papermaking drying energy supply coupling system, comprising the following steps:

[0008] Step 1: If the paper production needs to be increased, the paper machine speed is increased. If the original flue gas supply is maintained, the dryness and humidity detector at the paper machine outlet detects the dryness and humidity of the paper out of the hood. The detector shows that the dryness and humidity of the paper does not meet the process requirements, and more flue gas needs to enter the hood for drying to meet the flue gas volume required for drying the paper in the hood. If the gas turbine is already running at full load, the first regulating valve is controlled to gradually reduce its opening, and the opening of the first electric regulating valve of the hood air inlet pipeline is gradually increased to gradually increase the amount of flue gas entering the hood;

[0009] Step 2: If the first regulating valve is adjusted to the closed state, the flue gas volume provided is still not sufficient, and the flue gas temperature coming out of the gas hood is still very high, the flue gas discharged from the gas hood outlet is circulated back to the gas hood inlet for reuse, and the second electric regulating valve and the third electric regulating valve are opened. According to the dryness and humidity detection of the outlet, the opening of the two regulating valves is appropriately controlled to control the flue gas reflux volume, and the flue gas reflux is used to make it meet the flue gas volume required by the process;

[0010] Step 3: If the opening of the second electric regulating valve and the third electric regulating valve reaches the maximum and is still not satisfied, start the left afterburner, the first fresh air fan, the right afterburner, and the second fresh air fan. The fresh air fan is used to provide fresh air for the combustion aid, and the afterburner is used for afterburning;

[0011] Step 4: As the output of paper machines increases, the demand for steam from the drying cylinders also increases. The steam extraction electric valves of the boiler steam pipelines are gradually lowered to reduce the extraction of high- and low-pressure steam, giving priority to ensuring the steam volume of the drying cylinders.

[0012] Step 5: If the temperature parameter of the flue gas is too low after entering the gas hood, and the high-pressure steam boiler cannot operate within the high-efficiency operation curve range, but within the high-efficiency operation curve range of the low-pressure steam boiler, open the fourth electric regulating valve of the bypass, and close the fifth electric regulating valve at the inlet of the high-pressure steam boiler, so that the flue gas skips the high-pressure steam boiler and directly enters the low-pressure steam boiler. The steam generated by the low-pressure steam boiler is used to meet the steam demand of the drying cylinder first. After the steam generated by the low-pressure steam boiler enters the low-pressure separator, the steam parameters of the low-pressure separator are controlled, and the first electric valve is opened. The steam generated by the low-pressure separator enters the three-way valve and is mixed with the steam generated by the condenser. The three-way valve is controlled so that the generated steam meets the needs of the drying cylinder; if the steam generated by the low-pressure steam boiler is surplus, it can be extracted for sale to surrounding heat users or other process needs;

[0013] Step 6: If the temperature parameters of the flue gas after entering the hood are too low, and the low-pressure boiler in the fifth step is not enough to generate the steam required by the paper machine drying cylinder and the user, the afterburner and the fresh air fan can be started to perform appropriate afterburning to improve the flue gas parameters so that the boiler can generate the steam required for production;

[0014] If, in addition to supplying the steam demand of the paper machine drying cylinder, other high-pressure steam needs are required, the supplementary combustion amount is increased, the high-pressure steam boiler and the low-pressure steam boiler are started at the same time, the eleventh electric regulating valve is closed, and the extraction valve is opened to meet the high-pressure steam demand of the plant area. At the same time, the steam generated by the low-pressure steam boiler passes through the low-pressure separator, opens the first electric valve and the second electric valve to enter the three-way valve, and mixes with the steam of condensed water to generate steam required to meet the drying cylinder;

[0015] If it is necessary to reduce the paper production, the paper machine will reduce its speed, reduce the amount of flue gas entering the hood, lower the first electric regulating valve at the hood inlet, and increase the opening of the first regulating valve to reduce the amount of flue gas entering the hood. At the same time, the second electric regulating valve and the third electric regulating valve and the left afterburner and the right afterburner for circulating flue gas do not need to be started. The high and low pressure steam extraction volumes are adjusted according to the steam demand of regional or surrounding heat users. If the demand for high pressure steam increases, the opening of the high pressure steam extraction valve is further expanded to extract more high pressure steam to provide to heat users, while the opening of the low pressure steam extraction valve is reduced to make more More low-pressure steam enters the low-pressure separator to fill the shortage of high-pressure steam; if all the steam generated by the high-pressure steam boiler is extracted, that is, the eleventh electric regulating valve is closed, in order to ensure the steam required by the drying cylinder, the opening of the low-pressure steam extraction valve is further adjusted, and more low-pressure steam enters the low-pressure separator. At the same time, the opening of the sixth electric regulating valve and the power of the water feed pump are adjusted to adjust the water inlet into the low-pressure separator. The steam generated by the low-pressure separator enters the three-way valve through the first electric valve and the second electric valve, and the ninth electric regulating valve and the tenth electric regulating valve are closed at the same time to generate the steam required by the drying cylinder;

[0016] If the demand for low-pressure steam in other areas of the plant increases, the opening of the low-pressure steam extraction valve will be further expanded to extract more low-pressure steam to provide to heat users, while the opening of the high-pressure steam extraction valve will be reduced to allow more high-pressure steam to enter the high-pressure separator to generate the steam required for the drying cylinder;

[0017] If the paper machine is shut down for maintenance, the gas turbine can continue to run. The first regulating valve of the gas hood can be closed, and the flue gas can directly enter the high-pressure steam boiler and the low-pressure steam boiler to increase the output of high-pressure steam and low-pressure steam. The eleventh electric regulating valve and the twelfth electric regulating valve entering the high- and low-pressure separators can be closed, and the generated steam can be used for other processes or sold to surrounding heat users.

[0018] The control method of the papermaking drying energy supply coupling system of the present invention utilizes the electricity generated by the gas turbine to meet the electricity demand of the paper mill, and if there is surplus electricity, it can be sold online; the high-temperature and high-pressure flue gas generated by the gas turbine enters the gas hood for drying. If the flue gas is insufficient, the opening of the regulating valve at the gas hood inlet is controlled to increase the flue gas supply. If it is still insufficient, the flue gas circulation pipeline can be opened and the opening of the regulating valve on the control pipeline can be controlled to realize the recycling of the flue gas, further improve the energy efficiency of the energy, and at the same time solve the energy demand of the gas hood. If there is still a shortage, start the left afterburner for afterburning to provide the required flue gas. Combined with the process characteristics of hood drying, this system realizes the recycling of energy on the one hand, improves the energy utilization efficiency, and on the other hand can also solve the steam demand under different outputs, with the characteristics of flexibility, applicability, and strong matching items. At the same time, the flue gas from the hood is further utilized and enters the high and low pressure steam boilers successively to generate high and low pressure steam. The flue gas from the boiler controls its flow direction in different seasons to solve the energy demand in different seasons. In summer, it enters the lithium bromide chiller for cooling in summer; in winter, it enters the heat exchanger or lithium bromide unit to generate hot water for heating in winter to solve the cooling and heating needs in different seasons. The steam generated by the high and low pressure steam boilers can optimize the control of the steam volume entering the high and low pressure separators and the steam extraction volume of the bypass according to the production output requirements of the paper machine and the heat requirements of other areas of the plant to meet the steam requirements of different working conditions and different areas. It realizes the hierarchical and differentiated utilization of energy and improves the utilization rate of energy. At the same time, it can match the energy required for production by controlling the process flow according to the energy demand of the working conditions.

[0019] The control method for the papermaking drying energy supply coupling system of the present invention utilizes clean natural gas energy to provide the required electricity, steam, and high-temperature flue gas, while realizing the cascade utilization of energy, effectively improving the energy utilization efficiency, and combining the characteristics of the paper machine drying process to optimize the energy supply process and control method so that it can match the different working conditions of the paper mill and the various energy requirements required for production. On the one hand, the paper mill realizes low-carbon, clean and efficient production, and on the other hand, it greatly improves the flexibility, matching and practicality of the energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a papermaking drying energy coupling system of the present invention;

[0021] Figure 2 yes Figure 1 A partial enlarged view of the middle A;

[0022] Figure 3 yes Figure 1 A partial enlarged view of point B in the middle;

[0023] Figure 4 yes Figure 1A partial enlarged view of point C in the middle;

[0024] Figure 5 yes Figure 1 A partial enlarged view of point D in the middle. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions, technical advantages and technical effects achieved by the present invention easier to understand, the specific implementation methods of the present invention will be clearly and completely described below.

[0026] See also Figure 1-Figure 5 The present invention provides a papermaking drying energy supply coupling system, comprising a gas turbine, and a high-pressure steam boiler, a high-pressure separator, a low-pressure steam boiler, a low-pressure separator, a left afterburner, a right afterburner, a first fresh air fan, a second fresh air fan, a first air hood outlet exhaust fan V31, a second air hood outlet exhaust fan V32, a lithium bromide unit, a heat exchanger, a condenser, a deaerator, a first high-pressure boiler feed pump, a second high-pressure boiler feed pump, a first low-pressure boiler feed pump, and a second low-pressure boiler feed pump connected to the gas turbine.

[0027] In addition, the present invention also provides a control method for a papermaking drying energy supply coupling system, comprising the following steps:

[0028] Step 1: If the paper mill needs to increase paper production due to performance development, the paper machine increases its speed, and the paper production increases, if the original flue gas supply is maintained, the dryness and humidity detector at the paper machine outlet detects the dryness and humidity of the paper out of the air hood. The detector shows that the dryness and humidity of the paper does not meet the process requirements, and more flue gas is required to enter the air hood for drying to meet the flue gas volume required for drying the paper in the air hood. If the gas turbine is already running at full load, the first regulating valve 101 can be controlled to gradually reduce its opening, and the opening of the first electric regulating valve 102 of the air inlet pipeline of the air hood can be gradually increased to gradually increase the amount of flue gas entering the air hood;

[0029] Step 2: If the first regulating valve is adjusted to the closed state, the amount of flue gas provided is still not enough, and the temperature of the flue gas coming out of the gas hood is still very high, the flue gas discharged from the gas hood outlet can be recycled back to the gas hood inlet for reuse, and the second electric regulating valve 201 and the third electric regulating valve 204 are opened. According to the dryness and humidity detection of the outlet, the opening of the two regulating valves is appropriately controlled to control the flue gas reflux amount, and the flue gas reflux is used to make it meet the flue gas amount required by the process;

[0030] Step 3: If the opening of the second electric regulating valve and the third electric regulating valve reaches the maximum and is still not satisfied, the left afterburner A02, the first fresh air fan V21, the right afterburner A03, and the second fresh air fan V22 can be started. The fresh air fan is used to provide fresh air for the combustion aid, and the afterburner is used for afterburning to supplement the high-temperature and high-pressure flue gas, providing sufficient flue gas flow for hood drying, so that the dryness and humidity of the paper meet the process requirements;

[0031] Step 4: If the steam demand of the drying cylinder further increases due to the increase in paper machine output, the electric steam extraction valve of the steam pipeline should be turned down or even shut down to reduce the extraction of high and low pressure steam, giving priority to ensuring the steam demand of the paper machine drying cylinder;

[0032] Step 5: If the temperature parameter of the flue gas is too low after entering the gas hood, and the high-pressure steam boiler cannot operate within the high-efficiency operation curve range, but is within the high-efficiency operation curve range of the low-pressure steam boiler, the fourth electric regulating valve 103 of the bypass is opened, and the fifth electric regulating valve 105 at the inlet of the high-pressure steam boiler is closed, so that the flue gas skips the high-pressure steam boiler and directly enters the low-pressure steam boiler. The steam generated by the low-pressure steam boiler is preferentially used to meet the steam demand of the drying cylinder. After the steam generated by the low-pressure steam boiler enters the low-pressure separator, the steam parameters of the low-pressure separator are controlled, and the first electric valve 307 is opened. The steam generated by the low-pressure separator enters the three-way valve 501 and is mixed with the steam generated by the condenser. The three-way valve is controlled so that the generated steam meets the needs of the drying cylinder. If the steam generated by the low-pressure steam boiler is surplus, it can be extracted for sale to surrounding heat users or other process needs.

[0033] Step 6: If the flue gas temperature parameters are too low to generate the steam required by the paper machine drying cylinder and the user, the afterburner and the third fresh air fan V23 can be started to perform appropriate afterburning to increase the flue gas parameters so that the boiler can generate the steam required for production; at the same time, the high-pressure steam boiler is closed and the low-pressure steam boiler is directly used to supply steam to the drying cylinder;

[0034] If, in addition to supplying the steam demand of the paper machine drying cylinder, other high-pressure steam demand is required, the supplementary combustion amount is increased to further improve the flue gas parameters, and the high-pressure steam boiler and the low-pressure steam boiler are started at the same time, the eleventh electric regulating valve 309 is closed, and the extraction valve 301 is opened to meet the high-pressure steam demand of the plant area. At the same time, the steam generated by the low-pressure steam boiler passes through the low-pressure separator, opens the first electric valve 307 and the second electric valve 305 to enter the three-way valve 501, and is mixed with the steam of condensed water to generate steam required to meet the drying cylinder;

[0035] If the paper mill needs to reduce paper production due to business strategy and the paper machine slows down, the amount of flue gas entering the hood can be reduced appropriately, and the first electric regulating valve 102 at the hood inlet can be lowered, while the opening of the first regulating valve 101 can be increased to reduce the amount of flue gas entering the hood. At the same time, there is no need to start the second electric regulating valve 201 and the third electric regulating valve 204 of the circulating flue gas and the left afterburner A02 and the right afterburner A03, that is, to meet the process requirements of the paper drying cylinder. At the same time, the steam demand of the drying cylinder is further reduced. In this way, the opening of the high-pressure and low-pressure steam pipeline extraction electric regulating valves can be increased, and the high and low pressure steam extraction volumes can be adjusted according to the steam demand of other areas of the plant or surrounding heat users to meet the different steam needs of users. If the demand for high-pressure steam increases, the extraction of high-pressure steam can be further expanded. The opening of the steam valve is adjusted to extract more high-pressure steam to provide to heat users, and at the same time, the opening of the low-pressure steam extraction valve is reduced to allow more low-pressure steam to enter the low-pressure separator to fill the shortage of high-pressure steam; if all the steam generated by the high-pressure steam boiler is extracted, that is, the eleventh electric regulating valve 309 is closed, in order to ensure the steam required by the drying cylinder, the opening of the low-pressure steam extraction valve 302 can be further adjusted to allow more low-pressure steam to enter the low-pressure separator, and at the same time, the opening of the sixth electric regulating valve 312 and the power of the water supply pump are adjusted to adjust the water intake into the low-pressure separator, and the steam generated by the low-pressure separator enters the three-way valve 501 through the first electric valve 307 and the second electric valve 305, and at the same time, the ninth electric regulating valve 303 and the tenth electric regulating valve 304 are closed to generate the steam required by the drying cylinder;

[0036] If the demand for low-pressure steam in other areas of the plant increases, the opening of the low-pressure steam extraction valve can be further expanded to extract more low-pressure steam to provide to heat users, while reducing the opening of the high-pressure steam extraction valve to allow more high-pressure steam to enter the high-pressure separator to generate steam required for the drying cylinder;

[0037] If the paper machine of the paper mill is shut down for maintenance, the gas turbine can continue to run, close the first regulating valve 101 of the gas hood, and the flue gas directly enters the high-pressure steam boiler and the low-pressure steam boiler to increase the output of high-pressure steam and low-pressure steam, and close the eleventh electric regulating valve 309 and the twelfth electric regulating valve 310 entering the high- and low-pressure separators, and the generated steam is used for other processes or sold to surrounding heat users or surrounding heat users.

[0038] The working principle of the energy coupling system for papermaking drying of the present invention is as follows: a part of the high-temperature flue gas generated by the combustion engine enters the drying part of the paper machine through the pipeline and the regulating valve 102, and then a part enters the air inlet of the dry air hood of the paper machine through the three-way pipeline, and the other part enters the air inlet of the wet air hood, which is used for impact drying of paper. The first pressurized fan V11 and the second pressurized fan V12 are respectively arranged at the air inlet of the dry air hood and the air inlet of the wet air hood, so as to provide assistance to the flue gas entering the air hood, and at the same time, the pressurized fan V12 is used to pressurize the paper. The pipelines before and after the fan are connected in parallel with a branch. The dry gas hood pipeline includes the afterburner A02, the first fresh air fan V21, and an electric valve. The wet gas hood pipeline includes the afterburner A03, the second fresh air fan V22, and an electric valve. When the flue gas is insufficient, afterburning is performed to provide the required sufficient flue gas. At the same time, fans are set at the outlets of the dry and wet hoods to discharge the flue gas mixed with water vapor after drying. There is a pipeline directly connected between the exhaust flue gas pipeline of the dry gas hood and the air intake pipeline. At the same time, an electric regulating valve is set on the pipeline. The throttle valve 201, the exhaust flue gas pipeline of the wet hood is directly connected to the air intake pipeline, and an electric regulating valve 202 is arranged on the pipeline. The exhaust flue gas temperature is still relatively high and can be recycled. It returns to the air intake pipeline through the direct-connected pipeline and then enters the hood for paper drying. The flow rate of the flue gas returning to the air inlet can be controlled by the regulating valve on the pipeline to meet the flue gas volume required by the paper machine at different outputs. The flue gas discharged from the dry and wet hoods finally enters the exhaust main pipe of the hood. The flue gas of the exhaust main pipe and part of the flue gas directly discharged by the combustion engine are mixed in the mixer. In front of the mixer, the exhaust main pipe of the hood is provided with a combustion aid for supplementary combustion to increase the temperature, pressure and flow rate of the flue gas. The flue gas discharged from the mixer enters the high-pressure steam boiler and the low-pressure steam boiler in turn to generate high-pressure steam and low-pressure steam in turn. The steam discharged from the high-pressure steam boiler and the low-pressure steam boiler enters the high-pressure separator and the low-pressure separator respectively. A bypass and a regulating valve are arranged at the same time. Part of the steam can be extracted for other purposes according to the working conditions.

[0039] The high-pressure and low-pressure separators are connected to the feed water pipeline. The feed water enters the high-pressure and low-pressure separators through the regulating valves respectively. The steam and feed water are mixed in the separators to separate steam and water. The steam comes out from the exhaust port of the separator. The amount of feed water is controlled by adjusting the opening of the regulating valve, thereby controlling the steam parameters discharged from the separator. The steam discharged from the high-pressure separator passes through the pipeline and the electric regulating valve, enters the three-way valve, and then enters the dryer steam main pipe. The steam discharged from the low-pressure separator directly enters the dryer steam main pipe. The steam from the dryer steam main pipe enters the dryer and is used for paper drying in the dryer. The condensed water discharged from the separator returns to the boiler through the pipeline and the feed water pump respectively. The water separated by the high-pressure separator returns to the high-pressure steam boiler through the high-pressure boiler feed water pump (in parallel, one for use and one for backup). The water separated by the low-pressure separator returns to the low-pressure steam boiler through the low-pressure boiler feed water pump (in parallel, one for use and one for backup).

[0040] The steam-water mixture discharged after the drying cylinder enters the condenser, where steam and water are separated. The separated steam enters the three-way valve. The ratio of the steam from the high-pressure separator and the steam separated from the condenser is adjusted by controlling the three-way valve, so that the steam discharged from the three-way valve meets the needs of the drying cylinder; the water generated after the steam-water separation in the condenser enters the high-pressure separator and the low-pressure separator respectively through the condensate water pump (one for use and one for standby, used in parallel), and electric regulating valves are respectively arranged on the pipelines to control the amount of water entering the separator; at the same time, a make-up water system is arranged, which includes an inlet pipe, a deaerator, a first make-up water feed pump 1, and a second make-up water feed pump 2 (one for use and one for standby, used in parallel). When water enters the deaerator, part of the water is extracted from the steam extraction pipeline of the low-pressure steam boiler and enters the deaerator. The water coming out of the deaerator enters the high- and low-pressure separator water inlet main pipe through the make-up water feed pump, and then enters the high- and low-pressure separators respectively.

[0041] The control method for the paper drying energy supply coupling system of the present invention realizes the cascade utilization of energy, further improves the energy utilization efficiency, realizes the mutual conversion of multiple energy sources through optimized control, and meets the energy demand of different working conditions of the enterprise.

[0042] The control method of the papermaking drying energy supply coupling system of the present invention utilizes the electricity generated by the gas turbine to meet the electricity demand of the paper mill, and if there is surplus electricity, it can be sold online; the high-temperature and high-pressure flue gas generated by the gas turbine enters the gas hood for drying. If the flue gas is insufficient, the opening of the regulating valve at the gas hood inlet is controlled to increase the flue gas supply. If it is still insufficient, the flue gas circulation pipeline can be opened and the opening of the regulating valve on the control pipeline can be controlled to realize the recycling of the flue gas, further improve the energy efficiency of the energy, and at the same time solve the energy demand of the gas hood. If there is still a shortage, start the left afterburner for afterburning to provide the required flue gas. Combined with the process characteristics of hood drying, this system realizes the recycling of energy on the one hand, improves the energy utilization efficiency, and on the other hand can also solve the steam demand under different outputs, with the characteristics of flexibility, applicability, and strong matching items. At the same time, the flue gas from the hood is further utilized and enters the high and low pressure steam boilers successively to generate high and low pressure steam. The flue gas from the boiler controls its flow direction in different seasons to solve the energy demand in different seasons. In summer, it enters the lithium bromide chiller for cooling in summer; in winter, it enters the heat exchanger or lithium bromide unit to generate hot water for heating in winter to solve the cooling and heating needs in different seasons. The steam generated by the high and low pressure steam boilers can optimize the control of the steam volume entering the high and low pressure separators and the steam extraction volume of the bypass according to the production output requirements of the paper machine and the heat requirements of other areas of the plant to meet the steam requirements of different working conditions and different areas. It realizes the hierarchical and differentiated utilization of energy and improves the utilization rate of energy. At the same time, it can match the energy required for production by controlling the process flow according to the energy demand of the working conditions.

[0043] The control method for the papermaking drying energy supply coupling system of the present invention utilizes clean natural gas energy to provide the required electricity, steam, and high-temperature flue gas, while realizing the cascade utilization of energy, effectively improving the energy utilization efficiency, and combining the characteristics of the paper machine drying process to optimize the energy supply process and control method so that it can match the different working conditions of the paper mill and the various energy requirements required for production. On the one hand, the paper mill realizes low-carbon, clean and efficient production, and on the other hand, it greatly improves the flexibility, matching and practicality of the energy system.

[0044] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A control method for a papermaking drying energy supply coupling system, characterized in that: The energy supply coupling system for papermaking drying includes a gas turbine, and a high-pressure steam boiler, a high-pressure separator, a low-pressure steam boiler, a low-pressure separator, a left afterburner, a right afterburner, a first fresh air fan, a second fresh air fan, a first gas hood outlet exhaust fan, a second gas hood outlet exhaust fan, a lithium bromide unit, a heat exchanger, a condenser, a deaerator, a first high-pressure boiler feed pump, a second high-pressure boiler feed pump, a first low-pressure boiler feed pump, and a second low-pressure boiler feed pump connected to the gas turbine; The control method for the papermaking drying energy supply coupling system comprises the following steps: Step 1: If the paper production needs to be increased, the paper machine speed is increased. If the original flue gas supply is maintained, the dryness and humidity detector at the paper machine outlet detects the dryness and humidity of the paper out of the hood. The detector shows that the dryness and humidity of the paper does not meet the process requirements, and more flue gas needs to enter the hood for drying to meet the flue gas volume required for drying the paper in the hood. If the gas turbine is already running at full load, the first regulating valve is controlled to gradually reduce its opening, and the opening of the first electric regulating valve of the hood air inlet pipeline is gradually increased to gradually increase the amount of flue gas entering the hood; Step 2: If the first regulating valve is adjusted to the closed state, the flue gas volume provided is still not sufficient, and the flue gas temperature coming out of the gas hood is still very high, the flue gas discharged from the gas hood outlet is circulated back to the gas hood inlet for reuse, and the second electric regulating valve and the third electric regulating valve are opened. According to the dryness and humidity detection of the outlet, the opening of the two regulating valves is appropriately controlled to control the flue gas reflux volume, and the flue gas reflux is used to make it meet the flue gas volume required by the process; Step 3: If the opening of the second electric regulating valve and the third electric regulating valve reaches the maximum and is still not satisfied, start the left afterburner, the first fresh air fan, the right afterburner, and the second fresh air fan. The fresh air fan is used to provide fresh air for the combustion aid, and the afterburner is used for afterburning; Step 4: As the output of paper machines increases, the demand for steam from the drying cylinders also increases. The steam extraction electric valves of the boiler steam pipelines are gradually lowered to reduce the extraction of high- and low-pressure steam, giving priority to ensuring the steam volume of the drying cylinders. Step 5: If the temperature parameter of the flue gas is too low after entering the gas hood, and the high-pressure steam boiler cannot operate within the high-efficiency operation curve range, but within the high-efficiency operation curve range of the low-pressure steam boiler, open the fourth electric regulating valve of the bypass, and close the fifth electric regulating valve at the inlet of the high-pressure steam boiler, so that the flue gas skips the high-pressure steam boiler and directly enters the low-pressure steam boiler. The steam generated by the low-pressure steam boiler is used to meet the steam demand of the drying cylinder first. After the steam generated by the low-pressure steam boiler enters the low-pressure separator, the steam parameters of the low-pressure separator are controlled, and the first electric valve is opened. The steam generated by the low-pressure separator enters the three-way valve and is mixed with the steam generated by the condenser. The three-way valve is controlled so that the generated steam meets the needs of the drying cylinder; if the steam generated by the low-pressure steam boiler is surplus, it can be extracted for sale to surrounding heat users or other process needs; Step 6: If the temperature parameters of the flue gas after entering the hood are too low, and the low-pressure boiler in the fifth step is not enough to generate the steam required by the paper machine drying cylinder and the user, the afterburner and the fresh air fan can be started to perform appropriate afterburning to improve the flue gas parameters so that the boiler can generate the steam required for production; If, in addition to supplying the steam demand of the paper machine drying cylinder, other high-pressure steam needs are required, the supplementary combustion amount is increased, the high-pressure steam boiler and the low-pressure steam boiler are started at the same time, the eleventh electric regulating valve is closed, and the extraction valve is opened to meet the high-pressure steam demand of the plant area. At the same time, the steam generated by the low-pressure steam boiler passes through the low-pressure separator, opens the first electric valve and the second electric valve to enter the three-way valve, and mixes with the steam of condensed water to generate steam required to meet the drying cylinder; If it is necessary to reduce the paper production, the paper machine will reduce its speed, reduce the amount of flue gas entering the hood, lower the first electric regulating valve at the hood inlet, and increase the opening of the first regulating valve to reduce the amount of flue gas entering the hood. At the same time, the second electric regulating valve and the third electric regulating valve and the left afterburner and the right afterburner for circulating flue gas do not need to be started. The high and low pressure steam extraction volumes are adjusted according to the steam demand of regional or surrounding heat users. If the demand for high pressure steam increases, the opening of the high pressure steam extraction valve is further expanded to extract more high pressure steam to provide to heat users, while the opening of the low pressure steam extraction valve is reduced to make more More low-pressure steam enters the low-pressure separator to fill the shortage of high-pressure steam; if all the steam generated by the high-pressure steam boiler is extracted, that is, the eleventh electric regulating valve is closed, in order to ensure the steam required by the drying cylinder, the opening of the low-pressure steam extraction valve is further adjusted, and more low-pressure steam enters the low-pressure separator. At the same time, the opening of the sixth electric regulating valve and the power of the water feed pump are adjusted to adjust the water inlet into the low-pressure separator. The steam generated by the low-pressure separator enters the three-way valve through the first electric valve and the second electric valve, and the ninth electric regulating valve and the tenth electric regulating valve are closed at the same time to generate the steam required by the drying cylinder; If the demand for low-pressure steam in other areas of the plant increases, the opening of the low-pressure steam extraction valve will be further expanded to extract more low-pressure steam to provide to heat users, while the opening of the high-pressure steam extraction valve will be reduced to allow more high-pressure steam to enter the high-pressure separator to generate the steam required for the drying cylinder; If the paper machine is shut down for maintenance, the gas turbine can continue to run. The first regulating valve of the gas hood can be closed, and the flue gas can directly enter the high-pressure steam boiler and the low-pressure steam boiler to increase the output of high-pressure steam and low-pressure steam. The eleventh electric regulating valve and the twelfth electric regulating valve entering the high- and low-pressure separators can be closed, and the generated steam can be used for other processes or sold to surrounding heat users.

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