JPH02254110A - Method for controlling optimum usage of energy in iron mill - Google Patents

Abstract

PURPOSE:To control the optimum usage of energy in an iron-mill and to reduce the energy cost by balancing the energy of gasses from a blast furnace, coke oven and converter and electric power, steam, etc., from generating equipments according to generation and demand. CONSTITUTION:The gases from the blast furnace 1, coke oven 2 and converter 3 are supplied through holders 4-6 as buffer and each gas is independently used or used by mixing with the other gas (10, 11, 14) and also used for power generating equipment 8. A part of the power thus generated and the extracted steam are supplied to an exhaust heat recovery generating equipment 9, and generated power is used 19. In the iron mill having the above energy constitution, from the generating condition of the above each gas, condition of the other steam generating sources 15 and demand condition of the gas, power and steam, the optimum energy balance containing supply 13 of oil, recovered power 18 and purchased power 20, is calculated by a computer. Based on this arithmetic result, each energy supplying source is controlled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is provided with a blast furnace, a coke oven, and a converter, and the by-product gas produced by each furnace is used to generate electricity in private thermal power generation equipment, or to generate steam. Pig making and steel making, in which excess steam from the business that is the source of generation is used to generate electricity using waste heat recovery power generation equipment, and the generated amount is supplied to the business that is the consumer of electricity.
This paper relates to an optimal energy operation and control method for achieving a low-cost balance between energy generated and consumed within a steelworks.

[Conventional technology]

Generally, there is an energy center in an ironworks/steelworks, and computers installed there provide various information (amount of by-product gas generated/used, amount of electricity generated/used/purchased). The amount 1 by-product gas holder level, etc.) is displayed on the information display screen, and based on that, the operator can calculate various energies (blast furnace gas BFG, coke oven gas C).
The situation was monitored and managed by intuition (OG, diluted p-gas LDG, oil, steam, and electricity), and each facility was operated using a medium-term operation plan hand-drawn using large-scale calculations. .

[Problem to be solved by the invention]

However, each factory (office) within a steelworks operates according to its own production schedule, but each operates with short-term modifications to its plans, and each plant (office) operates according to its own production schedule. Since the conditions of steel mills are intricately related to each other, it is difficult to accurately grasp the status of energy generation and consumption throughout the entire steelworks. This results in a very heavy burden on the operator. Furthermore, since there is a large amount of data, it is impossible to plan everything using nonlinear programming, and medium-term planning cannot follow the production schedule. For this reason, it is not possible to develop an optimal energy management method that matches actual results. As a result, this led to the dissipation of by-product gas and the purchase of more electricity than the electricity purchase contract amount (hereinafter also referred to as demand over), which resulted in increased energy purchasing costs and energy losses. .

The present invention solves the problems in the conventional technology, balances the energy generation and consumption of the entire steelworks, and prevents unnecessary dissipation of by-product gas and demand overflow, thereby improving the overall energy efficiency. The purpose of this project is to use computers to realize an optimal energy operation control method for steel plants that can reduce energy costs.

[Means to solve the problem]

To achieve the above object, the present invention provides blast furnace gas from the blast furnace gas holder, coke oven gas from the coke oven gas holder, converter gas from the converter gas holder, and oil from the oil source, either individually or selectively. A private thermal power generation facility that functions as a power generation source and a steam extraction source, a business office that serves as a steam generation source, and the steam extracted from the private thermal power generation facility and the business office that serves as a steam generation source. Exhaust heat recovery power generation equipment that functions as a power generation source by separately or selectively distributing steam generated from In order to realize an optimal energy operation control method for a steelwork in a steelworks equipped with a plant, a business office as a consumer of each of the above-mentioned gases and their mixed gases, and a business office as a consumer of steam. Equipped with a computer.

[Effect]

The computer is given information about the operation of each plant, including blast furnaces, coke ovens, and converters.
Changes in the generation status of each gas in the converter and its distribution to private thermal power generation equipment, changes in electricity demand at business establishments as electricity consumers, and changes in demand for each gas and their mixed gases. By predicting trends in steam generation and demand, the balance of electricity, gas, and steam is calculated, and the upper and lower limits of the gas storage level in each gas holder are not exceeded, and wasteful release of each gas and steam does not occur. In order to balance the above-mentioned balance within limits and outside power purchase contract amounts, the amount of each gas and oil to be distributed to private thermal power generation equipment, the amount of insufficient power to be accommodated from outside, and the amount of electricity to be accommodated to outside. Surplus electricity amount, electricity,
The amount demanded by each gas and steam consumer is calculated and instructed to the operator in a direction that will reduce the required overall cost.

Operators can use this control to achieve optimal energy usage in steel plants.

In other words, the present invention provides long-term production a of each office within a steelworks.
An operation method that reduces losses due to by-product gas dissipation due to demand overload, etc. and energy purchase costs by predicting energy balance using a computer based on J-picture information, recent operation information 1 performance information, and electricity contract details (private thermal power generation It can be said that it determines equipment, exhaust heat recovery power generation equipment, and factory operation/stop timing, displays various information on a display, and provides operator guidance. In calculating this amount, we make effective use of energy by making effective use of by-product gas holders installed in the plant, private fire saw power generation equipment, and exhaust heat recovery power generation equipment, and adjust the power generation amount based on the power purchase strategy. Offices) We are trying to optimize operational costs through operational adjustments.

〔Example〕

FIG. 1 is an energy flowchart of an iron-making and steel-making mill shown to explain one embodiment of the present invention.

In the figure, 1 is a blast furnace (which can be regarded as a business that produces blast furnace gas BFG as a by-product), 2 is a coke oven (which can be regarded as a business that produces coke oven gas COG as a by-product), and 3 is a business that produces coke oven gas COG as a by-product. Converter (can be regarded as a business that produces converter gas LDG as a by-product), 4 is a holder serving as a buffer for storing blast furnace gas BFG, 5 is a holder serving as a buffer for storing coke oven gas COG, and 6 is a holder serving as a buffer for storing coke oven gas COG. holder as a holder for storing converter gas LOG, 7 is nitrogen (N2) supply equipment, 8 is private thermal power generation equipment, 9 is exhaust heat recovery power generation equipment, and 0 is a business office as a factory that uses blast furnace gas BFG. (Hereinafter, each factory and equipment is considered a business office.) 11 is a group of factories that use coke oven gas COG, 12 is a gas mixer (mixed gas production equipment), 13 is oil supply equipment, and 14 is a group of factories that use mixed gas. , 15 is a factory group that is a steam generation source, 16 is a factory group that uses steam, 17 is a steam dissipation facility,
18 is a group of factories that generate electricity as a byproduct (business establishments where electricity can be recovered), 19 is a group of factories that use electricity, 20 is a power purchasing facility for purchasing insufficient electricity from electric power companies, etc.
Reference numeral 21 denotes a reverse transmission facility for returning surplus power to an electric power company or the like.

FIG. 2 is a flowchart showing the calculation procedure executed by the computer according to the present invention.

Next, an embodiment will be explained step by step with reference to FIGS. 1 and 2. First, in step S1 of FIG. 2, a computer (not shown) calculates the amount of each gas, electricity, and steam generated and used based on long-term production plan information from the host computer and recent operation information and performance information from other computers. The calculations for each factory are summarized to predict the amount of energy generated and used up to the bevel at a certain time, and then in step S2 of FIG. 2, the distribution of converter gas LDG is calculated. The converter gas LDG is generated from the converter 3 and is temporarily stored in the LDG boulder 6, from which the amount to be discharged after use is determined as follows. If the current amount to be paid out (the sum of the amount going to private thermal power generation equipment 8 x3 and going to mixer 12 < ff1 x 4)
If the storage level in the holder 6 is within the upper and lower limits within the predicted time, the current value is maintained. If the stockpiled level in the holder 6 exceeds the upper and lower limits, calculate the scheduled total amount to be paid out so that the number of adjustments of the total amount to be paid out is minimized, and set the amount going to the private thermal power generation equipment 8 x 3 to the current value. The amount of gas going to the mixer 12 x 4 is calculated based on the condition that it is maintained. If it cannot be determined under the above conditions, adjust the amount going to the private thermal power generation equipment 8 x 3 the amount of gas going to the mixer 12 x 4 to bring the storage level in the holder 6 within the upper and lower limits. If the stock level in the holder 6 exceeds the upper limit even if the payout amount is maximum, it will be unavoidable to dissipate (U
9) Do. The above can be expressed as follows.

■Decision variables: X3 (amount of gas going to private thermal power generation membrane #8), X4 (amount of gas going to mixer 12) ■Demand and supply balance: Y3 (given by the amount of converter gas LDG emitted) ~ v3
(Amount directed to storage in gas holder 6) = X4 + 3 represents the calculated value at the second point.■3 is the flow rate toward storage in the gas holder 6, U9 is the flow rate dissipated from the gas holder 6, JT
is the length of time during which the flow rate is considered constant, and the time length AT
The above-mentioned "i-th" in which "is calculated as a period" refers to the i-th with such a period as a unit. α is a conversion coefficient.

(i) Constraint condition (a) X4 is related to the IV gas supply and demand balance via the mixer 12, and affects the BFG supply and demand balance and the COG supply and demand balance.

(b) Z3 should not exceed the lower limit of gas holder 6. That is, if the lower limit of the gas boulder 6 is 23"" and the upper limit is 73"', then Z3"' ≦73・≦
It is necessary to satisfy the relationship of 23".

(c) X3 is related to the operating status of the private thermal power generation equipment 8.

(d) V3 may be a negative value (at this time, it corresponds to when gas is being discharged from the boulder 6).

(E) The amount of radiation U9 from the gas boulder 6 is normally O.

■If the emergency means 73'' exceeds 23'', use the gas holder 6.
radiates from.

Next, in step S3 of FIG. 2, M4! of the gas BFG and COG going to the mixer 12! : Calculate N'l. The mixed gas (M I That is, the second
Taking into account the amount of LDG destined for the mixer 12 determined in step S2 in the figure, and keeping the amount of nitrogen mixed in as it is at the current value, only the amount of mixed gas whose Woche index is set is the amount that is planned to be consumed. Calculate the amount of BFGCOG to be sent to mixer 12 required for production. The above can be expressed as follows.

■Decision variables: UI (BFG!>, U2 (COO amount)) ■Demand and supply harassment 7th: U1+U2+X4+X5=Y6 (Y
6 is given by the usage amount at the mixed gas usage factory 14) ■Constraints (a) Since Ul is related to the BFG supply and demand balance, there is a limit to the supply amount.

(b) Since U2 is related to the COG supply and demand balance, there is a limit to its supply amount.

(c) The index W, +, CW, . . . of the mixed gas (MIX gas) produced by the mixer 12 is controlled to be - constant. The weight index wM is determined by the calorie (CM) and density (ρ) of the MIX gas.

CM and ρ8 are determined by the composition of the MIX gas.

■Emergency measures In case of emergency, reduce Y6.

In step S4 of FIG. 2, the BFG allocation is calculated. That is, the BFG is generated from the blast furnace 1, and the BF
C. The amount stored in the holder 4 and dispensed from there according to the amount used is determined as follows.

The amount of gas going to the mixer 12 calculated in the second step S3, the amount going to the BFG-using factory group 10 at the time of calculation, and the amount going to the private thermal power generation equipment 8 are the same as the amount going to the holder 4 within the predicted time. If the gas storage level is within the upper and lower limits, the system is maintained to go to the private thermal power generation facility 8. If the gas storage level in the holder 4 exceeds its upper and lower limits, the total amount scheduled for dispensing is calculated so that the number of adjustments is minimized, and the amount going to the private thermal power generation stage [8 is adjusted based on it. Even if the amount going to the private thermal power generation equipment 8 is the maximum value, if the gas storage level of the holder 4 exceeds the upper limit, it will be dissipated, and if the level of the holder 40 exceeds the lower limit, the amount of gas going to the mixer 12 will be It does not decrease to an amount that does not exceed the lower level limit. As a result, the amount of mixed gas decreases, and since B I"G has low calories, BF
As G decreases, the mixed gas calorie becomes relatively higher than the set value, so nitrogen and COG are added to compensate for this.
The amount of each gas going to the mixer 12 is recalculated by increasing the amount of gas. If it still cannot be compensated, limit the load B
Reduce the amount going to FG-using factory 10. The above can be expressed as follows ■Decision variable: X1 (amount of gas going to private thermal power generation equipment 8), X5 (nitrogen) ■Demand and supply balance: Y 1 = v 1 = U 1 + Y
, 1 + represents the gas l1tk storage level in the gas holder 4, 71° represents its initial value, and Zl' represents the calculated value at the i-th position. (1) 1 is the flow rate toward storage in the gas holder 4, Ul is the flow rate dissipated from the gas holder 4, and α is the conversion coefficient.

(2) Constraints (a) Ul is related to the M gas supply and demand balance via the mixer 12.

(b) Zl should not exceed the upper and lower limits of the gas holder 4. That is, the lower limit of the gas holder 4 is set to 71''゛0,
If the upper limit is Zlffia''', then Zl''. ≦71″≦
Z1. It is necessary to satisfy the relationship ``'.

(c) Vl may be a negative value (at this time, this corresponds to when gas is being discharged from the holder 4).

(d) The amount of radiation U7 from the gas holder 4 is normally O.

■Emergency measures (a) Decrease the amount of gas U1 directed to the mixer 12.

(b) Decrease the usage amount Y4 at the factory 10.

(c) When 21' exceeds 21'', the gas radiates from the gas holder 4.

In step S5 in FIG. 2, the COG allocation is calculated. That is, COG is generated from the coke oven 2,
- The amount is temporarily stored in the COG holder 5, and the amount to be paid out from there according to the usage amount is determined as follows. The amount of gas destined for the mixer 12 calculated in step S3 in FIG.
Then, if the stock level of the holder 5 is within the upper and lower limits within the predicted time, the amount that will go to the COG-using factory group II and the amount that will go to the private thermal power generation facility 8 at the time of calculation remains the same as the amount that will go to the private thermal power generation facility 8. maintain. If the storage level in the holder 5 exceeds its upper and lower limits, the total payout schedule is calculated so that the number of adjustments is minimized, and the amount going to the private thermal power generation stage wj8 is adjusted based on it.

Even if the amount going to the private thermal power generation facility 8 is at the maximum value, if the storage level in the holder 5 exceeds the upper limit, it will be dissipated.
Even if it is the minimum value, if the storage level in the holder 5 exceeds the lower limit, the load will be limited and the amount of COG used will be reduced. The above can be expressed as follows.

■Decision variable: X2 (amount of gas going to private thermal power generation equipment 8) ■Demand and supply balance: Y2 (coke oven gas generation 1
t) - V2 (amount directed to storage in gas holder 5) = U2
+Y5 ±

However, Z2 represents the gas storage level in the gas holder 5, 72° represents its initial value, and Z2'' represents the first calculated value. Its instantaneous amount dissipated from,
α is a conversion coefficient.

(2) Constraint condition (a) U2 is related to the M gas supply and demand balance via the mixer 12.

(b) Z2 should not exceed the upper and lower limits of the gas holder 5. That is, if the lower limit of the gas holder 5 is 22'' and the upper limit is 2211'', then Z2'''≦22'≦2
It is necessary to satisfy the relationship 21″a″. Furthermore, if there is a gas stockpiling plan, Z2 is increased to a given value.

(c) V2 may be a negative value (at this time, this corresponds to when gas is being discharged from the holder 5).

(d) The amount of radiation U8 from the gas holder 5 is normally O.

■Emergency measures (a) Reduce lY5 used in factory 11.

(b) Z2" is 22"'. When the amount exceeds the amount, the gas is released from the gas holder 5.

In step S6 of FIG. 2, calculate the input and output of the private thermal power generation equipment 8 and the exhaust heat recovery power generation membrane (#9. First, go to the private thermal power generation equipment 8 <1., DC, BFG, C
Based on the OO amount, the minimum required amount as the amount X7 that can be extracted from the private thermal power generation equipment 8 in order to maintain the power generation amount at the time calculated and compensate for the lack of steam in the steam system. In order to cover this, calculate the amount of oil lX6 that goes to the private thermal power generation equipment 8. However, the above steam shortage is calculated by the usage amount Y8 in the steam-using factory group 16 and the minimum steam amount (U
It is the value obtained by subtracting the generation amount Y7 from 3). If there is a shortage or surplus of steam, the amount of power generated by the private thermal power generation equipment 8 is adjusted to adjust the amount of extracted air X7. If the bleed air lX7 from the private thermal power generation membrane (#8) is O, but there is still steam, it will be dissipated using the dispersion equipment 17.The above can be expressed as follows.

■Decision variables: X6 (amount of oil), X7 (amount of steam that can be extracted from private thermal power generation equipment 8) ■Demand and supply balance:
Y7 (steam generation amount at factory 15) + X7 = Y8 + U6 +
U3 (Steam generation amount Y7 and factory] Usage amount Y8 in 6 is given) ■Constraints (a) Steam 1iX that can be extracted from private thermal power generation membrane m8
7 is due to the operation of private thermal power generation installation 8, so X1~
X3. Depends on X6. Further, there is a maximum limit to the amount of steam X7 that can be extracted.

(b) U3 is O when the exhaust heat recovery power generation equipment 9 is inactive. When the exhaust heat recovery power generation equipment 9 is in operation, U3 must be between U3"' and U3'"3.

(d) The amount of radiation U6 by the steam diffusion equipment 17 is preferably as small as possible.

(E) The operation and shutdown of the exhaust heat recovery power generation facility m9 cannot be changed frequently.

■Emergency measures Decrease the usage amount Y8 at the factory 16.

In step 7 of FIG. 2, the power balance is calculated. Assuming that the difference between the predicted electric power generation amount Y9 and the predicted electric power consumption YIO, and the amount of power generated by the private thermal power generation facility and the amount of power generated by the exhaust heat recovery power generation facility calculated in step 6 of Figure 2 is covered by electricity purchase and reverse transmission, the amount is calculated as follows: calculate. The above can be expressed as follows.

■Decision variable: Z4. Z5 ■Demand and supply balance: U4-1-U5+Y9+Z4=Z5+Y10 (Factory 1
Recovered electricity ¥9 in 8 and electricity usage f in factory 19
tY10 is given) ■Power generation amount in private thermal power generation equipment 8: The power generation amount is U
5, ■Power generation amount in the exhaust heat recovery power generation equipment 9: The power generation amount U 4
= K U 3 · U 3 (However, KU 3 is a constant) ■ Constraints (a) One of the electricity purchase amount Z4 and the reverse transfer 125 is 0, and the other is 0 or positive.

(0) The hourly cumulative value of the electricity purchase amount Z4 has a maximum limit value, and varies depending on the season and time of day.

In step S8 of FIG. 2, step S7 of FIG.
The amount of electricity purchased and retransferred calculated in the above is corrected to the optimal value using the electricity purchasing strategy devised based on each energy cost. That is, FIG. 3 is a flowchart showing the procedure (details of step S8).

First, in step S80 of FIG. 3, it is determined whether the reverse feed amount is larger than the set value, and if the reverse feed amount is larger than the set value, in step S81, the BF to the private thermal power generation facility 8 is
By reducing G, COG, LDG, oil amount, and amount of extracted air X7 from the private thermal power generation equipment 8, the power generation amount of the private thermal power generation equipment 8 and the power generation amount of the exhaust heat recovery power generation equipment 9 is reduced, and the amount of reverse feed is reduced. Keep it within the set value.

When the amount of reverse transmission is within the set value, the power purchase MIN strategy minimizes the amount of power purchased by the power purchase cost (used during times when the power purchase cost is high) and the amount of by-product gas is not dissipated within the contract power amount. There is a power purchase MAX strategy (used during times when the power purchase cost is low) that increases the amount of power purchased, and Ste Nobu S
In step S82, when the power purchase MIN strategy is adopted, in step S83, if the predicted power purchase amount is greater than the set value, the BFG, COC; LD for private thermal power generation facility 8 is selected.
By increasing G, the amount of oil, and the amount of extracted air X7 from the private thermal power generation membrane +118, the power generation amount of the private thermal power generation equipment 8 and the power generation amount of the exhaust heat recovery power generation equipment 9 are increased, and the amount of purchased electricity is decreased to the set value.

Further, in step S82, if the power purchase MAX strategy is adopted, in step S84, the private thermal power generation equipment 8
By reducing the amount of COG, oil, and amount of air extracted from the private thermal power generation equipment 8, the amount of power generated by the private thermal power generation equipment 8 and the amount of power generated by the exhaust heat recovery power generation equipment 9 are reduced, and by-products are reduced within the contracted power amount. The amount of electricity purchased will be increased to the extent that gas is not released. However, if there is a stockpiling plan for the COG holder 5, the COC view destined for the private thermal power generation facility 8 is adjusted so as to approach that value.

In addition, in the power purchase MIN strategy and the power purchase MAX strategy, the minimum amount of COC or oil necessary for the operation of private thermal power generation equipment is also secured.

In step S9 of FIG. 2, the obtained results are displayed to the operator, and the operator performs control accordingly.

〔Effect of the invention〕

With this invention, it is possible to automate the decision-making of energy operation methods in steel works, thereby making it possible to save labor, and also to enable effective utilization without exceeding the upper and lower limits of the gas storage level of each gas holder, private thermal power generation equipment, etc. Energy saving effects can be achieved through highly efficient operation of waste heat recovery power generation equipment.

[Brief explanation of drawings]

FIG. 1 is an energy flowchart 1-8 of an iron-making and steelmaking mill shown to explain an embodiment of the present invention. FIG. 2 is a flowchart showing a calculation procedure executed by a computer according to the present invention. 1. FIG. 3 is a flowchart showing details of step S8 in FIG. 2. Explanation of symbols 1... Blast furnace, 2... Coke oven, 3... Converter, 4...
・Blast furnace gas holder, 5...Coke oven gas holder, 6
...Converter gas holder, 7...Nitrogen supply equipment, 8...
Private thermal power generation equipment, 9...Exhaust heat recovery power generation equipment, 10
... Factory group using blast furnace gas BFG, 11 ... Factory group using coke oven gas COG, 12 ... Gas mixer, 13
...Oil supply equipment, 14...Factory group using mixed gas, 15...Factory group serving as a steam generation source, 16...Factory group using steam, 17...Steam dispersion equipment, 1 day・・・
- Factory group that generates electricity as a by-product, 19... Factory group that uses electricity, 20... Power purchasing equipment, 21... Reverse feed equipment. Agent Patent Attorney Akio Namiki

Claims (1)

[Claims] 1) Blast furnace gas from a blast furnace gas holder serving as a buffer for storing blast furnace gas from a blast furnace; coke oven gas from a coke oven gas holder serving as a buffer for storing coke oven gas from a coke oven; Converter gas from the converter gas holder as a buffer for storing converter gas from the converter, and oil from the oil source, respectively or selectively, function as a power generation source and a steam extraction source. private thermal power generation equipment, a business establishment that serves as a steam generation source, and steam extracted from the private thermal power generation equipment and steam generated from the business establishment that serves as a steam generation source, respectively or selectively. Exhaust heat recovery power generation equipment that functions as a power generation source, a business office as a consumer of electricity generated from the private thermal power generation equipment and exhaust heat recovery power generation equipment, and a consumer of each of the gases and their mixed gases. In a steelworks that has a number of establishments, and an establishment that serves as a steam consumer, information regarding the operation of each establishment including the blast furnace, coke oven, and converter is given to the said blast furnace, coke oven, and converter. Changes in the state of generation of each gas in the furnace and its distribution to the private thermal power generation equipment, trends in the power demand at the business office as a consumer of electricity, and demand for each of the gases and their mixed gases. trends, trends in steam generation and demand,
By predicting this using a computer, the balance of electricity, each gas, and steam is calculated, and the upper and lower limits of the gas storage level in each gas holder are exceeded, the limit where wasteful dissipation of each gas and steam does not occur, and the external power is calculated. The amount of each gas and oil to be distributed to the private thermal power generation equipment, the amount of insufficient electricity to be accommodated from outside, and the amount of surplus electricity to be accommodated to outside, in order to balance the above balance within the limit that does not deviate from the purchase contract amount. , the amount of electricity, gas, and steam demanded by consumers is calculated and instructed by the computer in a direction that reduces the required overall cost, and the method is controlled accordingly.