KR101701949B1 - Method and system for cascade control of boiler - Google Patents

Abstract

Control of the boiler will be described. A flow compensator comprising a heat source side including a plurality of boilers, a load side including a heating load circulating at a heat source side, a hydro separator or a heat exchanger compensating a flow rate between a heat source side and a load side; And a control unit for calculating the flow rate of the heat source and the load on the basis of the heat amount of the boiler and determining the number of the boilers and the set temperature of the boiler, thereby eliminating the imbalance of the heating supply due to the fluctuation of the load without the flow sensor or the flow control valve Perform cascade control.

Description

TECHNICAL FIELD [0001] The present invention relates to a cascade control system for a boiler,

The present invention relates to a control system and method for a multi-boiler including a hydro separator or a heat exchanger for compensating a flow rate between a heat source side including a plurality of boilers and a load side including a plurality of heating loads.

In the case of existing individual boilers, it is possible to satisfactorily control the heating supply water to a desired temperature and to control satisfactorily by only the heat quantity control in the heat exchanger.

Compared to individual boilers, it includes a low-loss header that compensates the flow rate between the heat source side (primary side) including a plurality of boilers (multi-boiler) and the load side (secondary side) In the heating cascade system, there is a difference in the supply temperature or the return water temperature between the primary side and the secondary side due to the flow rate difference between the primary side and the secondary side. Therefore, it is difficult to control the heating supply temperature of the secondary side to a desired temperature only by controlling the simple heat quantity of the primary side boiler.

Also, when the heat exchanger is used for reasons such as the allowable pressure difference between the primary side and the secondary side, it is also difficult to control the heating supply temperature to a desired temperature.

In order to control the flow rate in the boiler system by the cascade control system, a method of using a flow sensor or a flow rate control valve is applied to the boiler. However, the detection by the flow sensor detects the flow of heated water including impurities such as sludge There is a problem of a decrease in durability and reliability.

Patent Document 1: Korean Patent Registration No. 10-1433084

Patent Document 1: Korean Patent Laid-Open Publication No. 10-2012-0110405

Patent Document 2: Korean Patent Laid-Open No. 10-2008-0050546

It is an object of the present invention to easily control a heating supply temperature of a load in response to a change in flow rate depending on a plurality of heating load states in a boiler.

Another object of the present invention is to determine the flow rate of the heat source side and the load side without a separate flow rate sensor or flow rate control valve and to calculate the heat amount required for heating supply so as to follow the heating supply set temperature of the load side, Control.

Yet another object of the present invention is to control a boiler system including a heat exchanger for compensating the flow rate between the heat source side and the load side.

It is another object of the present invention to solve the imbalance of the heating supply according to the state of the load without the flow sensor in the boiler system.

According to the present invention, the above-mentioned objects can be achieved by a heat exchanger comprising a heat source side including a plurality of boilers, a load side including a heating load circulating on the heat source side, a hydro separator or a heat exchanger for compensating a flow rate between the heat source side and the load side A flow compensation unit; And a control unit for calculating the flow rate of the heat source side and the load side based on the heat amount of the boiler to determine the number of the boilers to be operated and the set temperature of the boiler.

Further, according to the embodiment of the present invention, the flow compensating unit may be any one selected from a hydro separator or a heat exchanger. The flow rate compensating section may include a temperature detecting section for detecting the temperature of the heat source side and the temperature of the load side.

Further, according to an embodiment of the present invention, the control unit includes: a load side flow rate determination unit for determining and determining the flow rate on the load side; A required calorie determination unit for calculating and determining a required calorie for raising the load-side supply temperature to the target value at the load side flow rate; And a boiler operation log determination unit for determining and determining the operation log of the boiler from the required heat amount determined by the required heat amount determination unit and the maximum heat value of one boiler.

Further, according to an embodiment of the present invention, the control unit may include: a flow rate determiner for determining a flow rate on the heat source side in accordance with operation of N boilers; And a boiler total calorie determination unit for summing the combustion calorie information of each of the N boilers in a state where the temperature is stable after a lapse of time to determine a calorie sum.

According to the embodiment of the present invention, the control unit updates the hot water temperature setting of the boiler to the calculated value when the boiler hot water temperature set value is lower than the hot water temperature threshold of the boiler, And a boiler set temperature judging unit for increasing the number of boiler operations when the temperature is equal to or higher than a temperature limit value.

Further, according to the embodiment of the present invention, the tap water temperature limit value of the boiler is about 80 캜.

According to the present invention, the above objects can be accomplished by a method comprising the steps of: 1) checking and calculating a load side flow rate FL; A second step of operating the boiler by determining the required heat quantity of the load side flow rate determined from the first step and the boiler operation number corresponding thereto; A third step of confirming the flow rate on the heat source side according to the operation of N boilers through the second step; And a fourth step of determining the boiler hot water setting temperature by calculating the flow rate on the heat source side identified in step 3 above.

A cascade control method for a boiler according to the present invention is a method for controlling a cascade of a boiler, the method comprising: determining a cycle time and updating a flow rate on a load side at each cycle time; performing the steps 2 to 4 again to update a required heat quantity, And a feedback step according to the change.

According to an embodiment of the present invention, when the boiler hot water set temperature set value calculated in step 4 is less than the hot water temperature threshold value of the boiler, the hot water temperature set value of the boiler is updated to the calculated value, And increasing the number of operations when the temperature exceeds the tap water temperature threshold value.

The present invention relates to a cascade boiler system including a low loss header for compensating a flow rate between a heat source side including a plurality of boilers and a load side having a plurality of heating loads, There is an effect that it is easy to control the heating supply temperature of the load side while coping.

The present invention is advantageous in that even in a system in which a heat exchanger is included between a heat source side and a load side due to a difference in pressure between a heat source side and a load side, .

INDUSTRIAL APPLICABILITY The present invention makes it possible to determine and determine an appropriate set temperature of a heat source during combustion, thereby enabling efficient operation of a heat source device such as a boiler. Thereby, energy reduction operation can be expected.

The present invention has the effect of eliminating the imbalance of the heating supply due to the fluctuation of the load on the cascade boiler system even in the absence of the flow sensor.

1 is a system block diagram of a cascade control system of a boiler according to an embodiment of the present invention.
2 is a system block diagram of a cascade control system of a boiler according to another embodiment of the present invention.
3 is a control block diagram of a cascade control system for a boiler according to an embodiment of the present invention.
4 is a flow chart showing an example of cascade control of a boiler according to an embodiment of the present invention.

The present invention includes a low loss header or a heat exchanger for compensating a flow rate between a heat source side (primary side) including a plurality of boilers and a load side (secondary side) having a plurality of heating loads A control system and method optimized for cascade boiler systems.

The present invention determines the flow rate of the primary and secondary without a separate flow sensor or a flow control valve, calculates the amount of heat required for the heating supply, and adjusts the heating supply set temperature of the load side (secondary side) A system and method for controlling temperature calculation.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings with reference to FIGS. 1 to 4. FIG.

1 is a system block diagram of a cascade control system of a boiler according to an embodiment of the present invention. 2 is a system block diagram of a cascade control system of a boiler according to another embodiment of the present invention.

FIG. 1 is an example in which a low loss header (LLH) is applied as a flow compensating unit, FIG. 2 is an example of a cascade control system of a boiler to which a heat exchanger (HE) is applied as a flow compensating unit, Means are different in that they are LLH (Low Lss Header) or HE (Heat Exchanger).

The known cascade boiler system is designed to connect several boilers in parallel to have a medium / large boiler capacity. It is harder to control than the case of using one medium- and large-sized boiler, but the heating can be controlled according to the situation There is an advantage, and the heating capacity can be expanded as needed.

The cascade system can apply a hydro separator as a flow compensating unit between a boiler side in which a plurality of boilers are connected in parallel and a load side that is an indoor piping unit. This is a means for preventing the phenomenon that the flow rate of the boiler side is lower than the required flow rate of the load side when the number of the boilers is partially operated depending on the situation.

The present invention can also be applied to a case where a heat exchanger is included between the primary side and the secondary side due to a difference in permissible piping pressure between the primary side and the secondary side.

A circulation pump (not shown) on the heat source side (primary side) is externally installed inside or below each boiler and is operated together when the boiler is operated. Therefore, the flow rate on the primary side changes with the number of boiler operation.

A circulation pump (not shown) separate from the primary circulation pump is installed on the load side (secondary side), and a plurality of heating loads are connected. Therefore, the flow rate of the secondary side also changes depending on the ON / OFF state or the open / close state of the heating load. When the heating load is high, more heat and more flow rate are needed. In order to systematically control and judge this in a cascade system, there is a method of controlling each boiler by using a flow sensor or a flow rate control valve, The influence of the sludge and the like contained in the heating water is hardly released, and the durability is deteriorated and the reliability against the control becomes a problem.

The present invention reliably controls the flow rate of the heat source side and the load side through the cascade control system of the boiler. This will be explained sequentially.

1 and 2, a cascade control system for a boiler according to an embodiment of the present invention includes a heat source side 100 including a plurality of boilers, a load side including a heat load circulating on the heat source side, (200), and a flow compensator (300) comprising a hydro separator or a heat exchanger for compensating the flow rate between the heat source side (100) and the load side (200).

Also. And a controller 400 for calculating the flow rate of the heat source side and the load side based on the heat quantity of the boiler to determine the number of operation of the boiler and the set temperature.

The flow compensating unit 300 may be selected from the hydro separator 301 as shown in Fig. 1, or the heat exchanger 302 as shown in Fig. 2, And a temperature detection unit.

3 is a control block diagram of a cascade control system for a boiler according to an embodiment of the present invention.

3, the control unit 400 includes a load side flow rate determination unit 410 for determining and determining the load side flow rate F _L , a required amount Q for raising the load side supply temperature from the load side flow rate to the target value T _LSET , _{HSET )} , a boiler operation number determining unit 420 for determining and determining the operation number N of the boiler from the required heat amount determined by the required heat amount determining unit 420 and the maximum heat amount of one boiler, And a determination unit 430 may be included.

The control unit 400 includes a flow rate determination unit 440 for determining a flow rate F _H on the heat source side in accordance with the operation of N boilers, a control unit 440 for summing the combustion calorie information of N boilers in a stable state after a lapse of time And a boiler total calorie determination unit 450 for determining the total calorific value (Q _H ).

When the boiler _hot water temperature set value T _HSET is lower than the _hot water temperature threshold value of the boiler, the control unit 400 updates the _hot water temperature setting of the boiler to the calculated value, and the calculated _{boiling hot} water temperature set value T _HSET is _stored in the boiler And a boiler set temperature judging unit 460 for increasing the boiler operation number N when the temperature of the hot water is above the hot water temperature threshold value of the boiler.

In this case, reference numeral 470 denotes a 'communication unit' for registering ID addresses as assignment slaves in a plurality of boilers and communicating with each other, and reference numeral 480 denotes a 'system setting temperature input unit'.

Cascade system control method for a boiler according to an embodiment of the present invention, the load flow (F _L) step 1 to check and calculating, a boiler operation number of the load flow rate required amount of heat (Q _HSET) and hence confirmed from Step 1 ( N) and determine the flow rate (F _H ) on the heat source side in accordance with the operation of N boilers through the second and the second steps of operating the boiler, and calculate the flow rate on the heat source side confirmed from step 3, (T _HSET ), the load side flow rate (F _L ) is updated at every cycle time, and the steps 2 to 4 are repeated to _calculate the required heat quantity (Q _HSET ), the movable number (N) _Lt ; _{RTI ID} = _0.0 > T _HSET ) < / RTI >

In addition, if the boiler _tumbling set temperature set value (T _HSET ) calculated in step 4 is less than the _boiling water temperature threshold value of the boiler, the _boiling water temperature setting of the boiler is updated to the calculated value, , And increasing the number of operations (N) in the case where the number of operations is N.

An example of a cascade control method of a boiler according to an embodiment of the present invention will be described in detail with reference to Fig.

4 is a flow chart showing an example of cascade control of a boiler according to an embodiment of the present invention.

When the operation of the cascade control system is started through the cascade control system of the boiler (S110), the control unit of the master including the slave processors sets the boiler set temperature to the target value (T _LSET (S111), it is determined whether the temperature changes of the components T _HS , T _HR , T _LS , and T _LR of the flow compensating unit LLH / HE are within a certain range (S112).

As a result of the determination, if the temperature change of the flow compensating unit is within a predetermined range, the following steps 1-4 (S113 to S117) are sequentially executed.

In the first step, the flow rate F _{L on the} load side is confirmed and calculated (S113), which is calculated and confirmed as follows.

Load side  Check flow (FL)

The pre-set initial operation number (for example, 1 to 2) is set by setting the load side set temperature (T _LSET ) to the boiler _hot water temperature.

After a certain time has elapsed, the load side flow rate (F _L ) is calculated in accordance with the following equation while the temperature of each part of the flow compensation section (LLH / HE) is stable.

The temperature and flow rate of each part of the flow compensation section (LLH / HE) have the following relationship.

F _H * (T _HS - T _HR ) = F _L * (T _LS - T _LR )

Here, the left term F _H * (T _HS - T _HR ) is the sum of the calories Q _H [kcal / min].

This value can be determined by summing up the combustion calorie information of each boiler by the control unit.

F _L = Q _H / (T _LS - T _LR ) [L / min]

In the second step, the required heat quantity (Q _HSET ) of the load side flow rate is confirmed and the number (N) of the boilers to be operated is determined to operate the boiler (S114 to S115).

Load side  Required calories ( Q _HSET ) And the boiler operation number (N)

Calculation of the required heat quantity (Q _HSET ) at the load side can be calculated by the following equation in order to raise the load side supply temperature to the target value (T _LSET ) at the current load side flow rate.

Q _HSET = (T _LSET - T _LR ) * F _L

Determination of boiler operation number (N) determines the operation number (N) from the required heat quantity on the load side and the maximum heat value of one boiler.

N = INT (Q _HSET / Q _MAX ) + 1

Where INT is an integer function. For example, when Q _HSET = 1700 kcal / min and Q _MAX = 600 kcal / min, the number of actuators is calculated as three.

- If N is greater than or equal to the installed number of boilers (N _MAX ), then N = N _MAX .

In the third step, the flow rate F _H on the heat source side according to the operation of N boilers is checked through step 2 (S116).

Depending on the operation of N boilers Heat source side  flux( FH ) Identification and calculation

First, the boiler of operation number (N) determined above is activated. The boiling temperature of each boiler operating at this time is set to the load side set temperature (T _LSET ) when there is a change in the number of operation, and the previous T _HSET value when there is no change in the operation number.

A predetermined time has elapsed after the flow rate compensation unit (LLH / HE) of each part temperature is to be summed in the control unit the N single boiler respective combustion heat information in the steady state heat sum (Q _H) for determination, and on the basis of a formula to the heat source side ( The primary flow rate F _H can be calculated.

F _H = Q _H / (T _HS - T _HR ) [L / min]

In step 4, the flow rate on the heat source side determined from step 3 is calculated to determine the boiler _hot water set temperature (T _HSET ) (S117).

Boiler Boil  Setting temperature ( THSET ) Calculation and determination

The _hot water temperature of each boiler can be determined from the above-described required heat amount (Q _HSET ) and the heat source side flow rate (F _H ) by the following equation.

Q _HSET = (T _HSET - T _HR ) * F _H Because of

T _HSET = (Q _HSET / F _H ) + T _HR to be.

It is determined whether the boiler _hot water temperature set value T _HSET calculated above is lower than the _hot water temperature threshold value of the boiler of 80 DEG C (S118). As a result of the determination, if it is less than the predetermined value, the hot water temperature setting of the boiler is updated to the calculated value (S120).

As a result of the determination, if the boiler _hot water temperature set value T _HSET is equal to or higher than the _hot water temperature threshold value of the boiler of 80 DEG C or more, the operation number N is increased by one and the flow amount confirmation on the heat source side in the third step is executed again in step S119.

The cascade control of the boiler according to the embodiment of the present invention may include a feedback control step (S121 to S123) according to the state change including the change of the boiler operation number during the combustion. It is not necessarily limited here.

The feedback control is performed in response to a state change during boiler combustion. The cycle time is determined and the load side flow rate F _L is updated for each cycle, and the steps 2 to 4 are executed again to update the required heat quantity Q _HSET , the movable number N and the boiler _hot water set temperature T _HSET ≪ / RTI >

For example, the boiler operation logarithmic change is that the determination and the determination result, if it is determined that the change (S123), temperature of this boiler set temperature and the boiler hot water setting (T _HSET) is equal to the step 2 to step 4 until the Lt; RTI ID = 0.0 > a < / RTI > Even if it is determined that there is no change in the number of operation of the boiler, it is periodically checked whether the boiler setting temperature and the boiler setting temperature T _HSET are equal (S122).

In the feedback control, it is preferable that the time from when the combustion is started to a predetermined calorie amount or after the calorie value is changed until the temperature of each part of the flow compensating unit (LLH / HE) is stabilized is set as the minimum period of the control value change. It is preferable not to update the control judgment values such as the load side flow rate FL and the required heat amount Q _HSET until the temperature value of the LLH / HE part is stabilized.

Further, it is possible to update the required heat quantity (QH _SET ), the number of operation (N), and the boiler _hot water set temperature (T _HSET ) by continuously updating the load side flow amount FL every cycle time and performing the steps 1 to 4 again.

The cascade control of the boiler according to the embodiment of the present invention is characterized in that in a cascade boiler system including a hydro separator for compensating a flow rate between a heat source side including a plurality of boilers and a load side having a plurality of heating loads, The control of the heating supply temperature on the load side can be facilitated while corresponding to the change in flow rate.

The cascade control of the boiler according to the embodiment of the present invention can be applied to a system in which a heat exchanger is included between the heat source side and the load side due to a difference in pressure of the piping pressure between the heat source side and the load side, Temperature control can be facilitated.

The cascade control of the boiler according to the embodiment of the present invention can determine and determine the appropriate set temperature of the heat source during combustion, and thus the boiler can be efficiently operated.

The cascade control of the boiler according to the embodiment of the present invention eliminates the imbalance of the heating supply due to the fluctuation of the load side without detecting the flow rate sensor in the cascade boiler system and accordingly opening and closing the flow rate control valve.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of illustration, .

100: heat source side 101: boiler
200: load side (heating load) 300: flow compensation unit
301: Hydro Separator (LLH: Low Lss Header)
302: Heat Exchanger (HE) 400:
410: FL flow rate determination unit 420: Required heat rate determination unit
430: Boiler operation log determination unit 440: FH flow rate determination unit
450: Boiler total calorie determination unit 460: Boiler set temperature determination unit
470: communication unit 480: system setting temperature input unit

Claims (8)

A flow compensator comprising a heat source side including a plurality of boilers, a load side including a heating load circulating on the heat source side, a hydro separator or a heat exchanger for compensating a flow rate between the heat source side and the load side;
A controller for calculating a flow rate of the heat source side and a load side on the basis of the heat amount of the boiler to determine the number of operation of the boiler and the set temperature; And
Wherein the control unit includes a total calorie determination unit for calculating a total calorific value (QH) by summing the combustion calorie information of each of the N boilers. The method according to claim 1,
Wherein the flow compensating unit is any one of a hydro separator and a heat exchanger, and the flow compensating unit includes a temperature detecting unit for detecting a temperature of a heat source side and a temperature of a load side. The method according to claim 1,
Wherein the control unit includes: a load side flow rate determiner for determining and determining a load side flow rate F _L ; A required calorie determination unit for calculating and determining a required heat quantity (Q _{HSET )} for raising the load side supply temperature to a target value (T _LSET ) at the load side flow rate; And
And a boiler operation number determining unit for determining and determining a number N of boilers to operate based on the required heat amount determined by the required heat amount determining unit and the maximum heat value of one boiler. The method according to claim 1 or 3,
Wherein the control unit comprises: a flow rate determiner for determining a heat source side flow rate (F _H ) according to the operation of N boilers; And a boiler total calorie determination unit for determining the total heat amount (Q _H ) by summing the combustion heat amount information of each of the N boilers in a state where the temperature is stable after a lapse of time. The method according to claim 1,
_Wherein the control unit _{updates the hot} water temperature setting of the boiler to a calculated value when the boiler _hot water temperature setting value (T _HSET ) is less than the _hot water temperature limit value of the boiler, and the calculated _hot water temperature setting value (T _HSET ) And a boiler set temperature judging unit for increasing the boiler operation number (N) in the case where the boiler temperature exceeds a threshold value. 6. The method of claim 5,
The tap water temperature limit value of the boiler is about 80 캜. A step 1 for checking and calculating the load side flow rate (F _L ); A second step of operating the boiler by determining the required heat quantity (Q _HSET ) of the load side flow rate determined from the first step and the boiler operation number (N) accordingly; A step (3) of confirming the heat source side flow rate (F _H ) according to the operation of N boilers through the second step; And a fourth step of determining a boiler _hot water setting temperature (T _HSET ) by calculating a flow rate on the heat source side identified in step 3 above. 8. The method of claim 7,
The _hot water temperature setting value of the boiler is updated to the calculated value when the boiler _hot water set temperature set value T _HSET calculated in the step 4 is less than the _hot water temperature threshold value of the boiler, And increasing the number of actuators (N) if the number of the actuators is equal to or greater than a predetermined value.

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