JPS59176530A - Room-to-room low differential pressure ventilation power-saving control equipment - Google Patents

Abstract

PURPOSE:To keep the airtight capacity of a hot experimetal equipment or a radioactive waste material processing equipment by a method wherein the control of the minute pressure difference between rooms and the power saving control of ventilation are performed simultaneously. CONSTITUTION:In an air supply and discharge equipment in which a single draft chamber 2 or a plurality of such chambers is or are provided in a single room 1 so that the pressure difference between the interior of the room and the outside of the room is kept constant irrespective of whether or not the room is used and at the same time, the capacity of an air exhauster 3 is controlled according to the condition of the draft chamger 2, an ON-OFF damper 5 is interposed in an exhaust duct 4 for the draft chamber 2 so that the damper 5 is opened and closed in response to signals from a sensor 6 for detecting the use condition of the chamber 2 while a pressure difference adjust damper 8 is interposed in an air supply duct 7 leading to the room 1 so that the damper 8 is opened and closed in response to signals from a pressure difference detecting sensor 9 for detecting the pressure difference between the room and the outside the room. Further, variable air quantity blowers are used as an air exhauster 3 and an air supplier 10 and the quantities of air from the air exhauster 3 and the air supplier 10 are controlled by a microcomputer 11 on the bases of the use condition of the draft chamber 2, the periodical change in the pressure loss in the air supply and discharge system and the pressure difference between the interior of the room and the outside of the room so that the equipment is kept airtight.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to facilities that require high airtight performance, such as hot experimental facilities and radioactive waste processing facilities, and in which draft chambers for experiments or processing operations are installed. This invention relates to a power-saving control equipment for ventilation with a small differential pressure between rooms, which enables the simultaneous implementation of a small differential pressure control between rooms and a power-saving control of the ventilation in a facility.

Air conditioning equipment for facilities that require high airtight performance, such as hot experimental facilities and radioactive waste processing facilities, is used to supply clean air, purify exhaust air, and measure the amount of air travel in each room. Maintaining room pressure is fundamentally important. Regarding the maintenance of constant air travel volume and room pressure in each room, if this cannot be maintained, the problem of cross contamination between rooms will occur. Conventionally, this maintenance of constant air travel volume and room pressure was accomplished by installing constant air volume valves (commonly known as OVA units) on the air supply side and the exhaust side.

1~ However, when using this constant air volume valve, it is unavoidable that the pressure loss in the duct system changes over time, causing fluctuations in the balance. If it stops, a larger amount of air than the set amount of air will be distributed to other rooms, making it difficult to maintain a constant volume and constant room pressure. There is a basic problem in that this constant air flow valve is unsuitable due to its structure for control in places where static pressure of 70++ onAq or more cannot be applied to the CAV valve. Furthermore, if a draft chamber that requires forced exhaust air is installed in the room, a large negative pressure will suddenly occur in the room if this draft chamber is used, and the differential pressure will be controlled every time the grilling table is turned on or off. becomes complicated. Regarding the exhaust side fan of the primary draft chamber, if exhaust capacity is ensured when all draft chambers are in use and the fan is operated at all times at this design capacity, power will be wasted if there is an unused dry chamber.

The present invention was made with the aim of solving such problems, and is intended for facilities that require high airtight performance, such as hot experimental facilities and radioactive waste processing facilities, and which is equipped with facilities for experiments or processing operations. The purpose of the present invention is to provide a ventilation power-saving control equipment for ventilation with a slight differential pressure between rooms, which is capable of simultaneously carrying out the control of the slight differential pressure between rooms and the power-saving control of ventilation in a facility in which a draft chamber is installed. That is, the power-saving control equipment for ventilation with slight differential pressure between rooms according to the present invention, as shown in the drawings,
A plurality of draft chambers 2 are provided in the chamber,
In the air supply/exhaust equipment that maintains the differential pressure between the chamber 1 and the outside at a constant level regardless of whether or not the draft chamber 2 is used, and at the same time controls the exhaust capacity of the exhaust fan 5 according to the usage status of the draft chamber 2, each An on-off damper 5 is interposed in the exhaust duct 4 of the draft chamber 2, and the on-off damper 5 is opened and closed based on a signal from a sensor 6 that detects whether each draft chamber 2 is used. A supply air duct l-7Vrc differential pressure adjusting damper 8 is installed, and the opening of this differential pressure adjusting damper 8 is controlled based on a signal from a differential pressure detection sensor 9 that detects the differential pressure between indoors and outdoors. In addition, a variable air volume blower is used as each of the air blowers 10, and the air volume of the exhaust fan 5 and the air blower 10 is controlled based on the usage status of each draft chamber 2, the pressure loss over time of the air supply and exhaust system, and the indoor-outdoor differential pressure VC base. Microcomputer for practical use-11
It is characterized by the addition of.

In Fig. 1, in addition to a room 1 in which multiple draft chambers 2 are installed, rooms 1a, 1b, and 1c for other purposes are arranged side by side, and supply air is distributed to all of these rooms from a blower 1o. ,
This shows an example in which the exhaust air from all rooms is collected and exhausted from the exhaust fan filter, and a constant air volume and constant pressure is maintained by the constant air volume valves 132 for other rooms 1a to 1C. ing. In the equipment of the present invention, the chamber 1 is equipped with the differential pressure adjustment damper 8.
If the draft chamber 2 is in use, the supply air is introduced through the draft chamber 2, and if all of the draft chambers 2 are not in use, the exhaust air inside the chamber 1 is passed through the spare exhaust duct Za. After being guided to the filter unit 14, the air is discharged out of the system by the exhaust fan 5. The opening degree of the differential pressure adjustment damper 8 is controlled based on a signal from a differential pressure detection sensor 9 that detects the differential pressure between the inside and outside of the room 1, for example, the differential pressure between the room and the hallway. As will be described later, when the differential pressure adjusting damper 8 is fully open, the fully open signal is input to the microcomputer 11VC.

Each fume hood 2 has a sufficient internal space for processing and experimenting with materials such as radioactive materials that must be avoided from contamination. You can now close it manually. A sensor 6 is attached that operates in accordance with each opening/closing operation of the opening/closing door 16 or in a delayed manner on a separately provided on/off switch, and this sensor 6 detects whether each draft chamber 2 is in use or not in use. . The detection signal is sent to the relay board 17, which slowly opens and closes the on-off damper 5 interposed in the exhaust duct 4 of each drum chamber. This on-off damper 5 is an AC motor-driven damper 6- whose opening/closing time can be adjusted from 20 seconds to 20 minutes, and its opening/closing operation is made to be performed as slowly as possible in order to suppress fluctuations in the room pressure caused by its opening/closing.

On the other hand, the blower 5 and the blower 10 are variable air volume blowers that can change the air flow in a stepless manner, more specifically, they are blowers that change the rotational speed of the motor of each blower by control signals, or that control the pitch angle of the blades. Use a blower that changes depending on the signal. The figure shows an example in which the rotational speed of the blower motor is changed by a control signal by adding an inverter unit 18 that changes the power supply frequency. A control signal to the inverter unit 18 of each blower is output from the microcomputer 11 based on a control sequence described later. Microcomputer 1
Inputs to 1 include a usage status signal of the draft chamber from the relay board 17, a fully open signal of the differential pressure adjustment damper 8, a signal for measuring pressure loss over time in the duct system from the wind speed detector 20 attached to the main exhaust duct, etc. It consists of

Specific examples of sequence contents and calculation contents of the control system of the present invention will be explained below.

“Sequence contents of the control system of the present invention” (Room 11 1
monitor characteristics representative of the usage status of the fume hood. Characteristics representative of the usage state are detected by an opening/closing sensor 6 (specifically, a limit switch or a proximity magnet switch) of the opening/closing door of the draft chamber.

(2) Information from the sensor 6 is received by the relay board 17 and used as an input signal to the microcomputer 11.

This input signal is a voltage-free contact. The input signal received by the relay board 17 causes the corresponding on-off damper 5 to operate as slowly as possible by a motor drive.

(3) The differential pressure setting between room 1 and the hallway is determined by the static pressure balance of the air supply and exhaust ducts to room 1. At this time, the air supply amount and exhaust amount are the same. This slight differential pressure control is performed by adjusting the opening degree of the differential pressure regulating damper 8 in the air supply system.

When the damper 8 is fully opened during this opening adjustment, the signal from the full open limit switch installed on the damper 8 is input to the computer 11.

(4) To measure the decrease in air volume due to pressure loss in the duct system (particularly the filter), install a wind speed detector or air volume detector 2o on the downwind side of the collecting part of the exhaust system or the filter unit 14, and collect the analog signal from the micro This is an input signal to the computer 11. The signal of this wind speed or air volume detector 2o is 0~5v (DC) or 4~20v
A mA (DC) signal is inputted, and the microcomputer performs arithmetic operations to perform sampling 2 times during the sampling period, exclude the minimum and maximum values, and then find the average air volume using the 8 sampling values.

(5) The air supply/exhaust volume of room 1 changes depending on the use condition of the draft chamber/bar, but the minimum air volume (for example, 1150
C! MH) In order to maintain i, the number of exhaust ports in the draft chamber + 1 is installed so that indoor air can be sucked in even when the draft chamber is fully closed.

"Computation contents of the control system of the present invention" (The flow when this computation is performed by a microcomputer is shown in Figs. 2 to 11)
− Calculate the required supply and exhaust volume of the system by multiplying the exhaust air volume by the operating conditions. However, the required air supply amount and required exhaust amount for rooms other than room 1 are secured as fixed amounts.

Required supply air volume QB; Supply air volume in other rooms qe; Supply air volume per draft chamber a
1; Parameter indicating usage status; 1 Not in use; O Qc + corrected air volume In this case, when the full open limit switch of the differential pressure control valve 8 installed on the air supply side is on, the corrected air volume Qc is set to the required supply. Add to air volume. When the fully open limit switch is OFF, Qc
−〇. When the corrected air volume is added, it is checked each time that the supplied air volume does not exceed the design air volume of the fan 10, and if it does, it is set as the design air volume.

~10- Required exhaust air volume R = RB 10Σqt When the full-open limit switch of the on-off damper 5 is also open, the on-off damper is fully open, but
If the fully open limit switch is closed, the on-off damper is in the middle of closing. Similarly, if 6, which represents the use state of the draft chamber, issues a close signal and the fully closed limit switch of the on-off damper 5, which slowly opens and closes the f motor drive, is also closed, the on-off damper is fully closed. ,
If the fully closed limit switch is open, the on-off damper is in the middle of opening. The time from full open to fully closed for the on-off damper, which opens and closes slowly, is divided into 10 equal parts, and the air volume for each equal part is stored in advance in the microcomputer, so that the draft chamber that is in the middle of opening and closing can be stored in the microcomputer in advance. The supply air volume and exhaust air volume per unit can be calculated using the following formula.

Ql, = qt x Er(N) However, Ef(N) indicates the air volume ratio to the air volume at the Nth fully open state when divided into 10 equal parts.

(3) Calculate the rotational speed of the air supply system ducts, air conditioners, and other pressure losses based on the required air supply air volume.

Air supply system pressure loss △PQo - △PQ1 + △PQ2 + △PF, ・(When fully open) △PQ - △PQ1 + △PQ2 (QlQo) 2 + △PF
(ctAo) - = (during operation), △PQ1 is from the air blower 10 to the CAV unit 16
The fixed part of the pressure loss ΔPQ2 in the duct at the junction leading to the chambers 1.1a, 1b, and 1cVC is the room 1.1a containing the CAV unit 16 from the blower 10 excluding the filter units ΔPF1 and ΔPQ1.
, 1b, the pressure loss of the duct up to IC2VC 5F1 is the pressure loss of the filter unit attached to the air supply side Calculate the rotation speed of the air blower 10 with respect to the air supply air flow Number of rotations of the air blower (foot speed control) NQ = KQN
QoX (△PQ//△pQ,) 2.4 to 20 mA signal output Here, NQo indicates the design rotation speed of the electric motor of the air blower 10 multiplied by KQ and the supply air volume coefficient.

(4) Calculate the total pressure loss and rotation speed of the exhaust system duct, filter unit, and other parts using the required exhaust air volume.

However, exhaust system pressure loss △PRo-△PR1+△PR; 10△PF2... (when fully open) △PR: △PR3 10△PR2 (R/Ro) to 2+p
, (R/Ro)... (during operation) Here, Ro'' Q6. Let R=Q.

However, △PBo is the pressure drop between chambers 1a, 1b, 1c, chamber 1 and the exhaust fan 5 including the filter unit 14, and △PR
1 is the pressure drop fixed valve for chambers 1a, 1b, 1c and the duct system from chamber 1 to exhaust fan 3, △PR2 is the filter unit △PF2 and △PR1e
Excluding the pressure loss in the duct from the exhaust fan 5 to rooms 1a, 1b, 1c and room 1, △PF2 is the pressure loss of the filter unit installed on the exhaust side, Calculate the rotation speed of the exhaust fan 6 for the exhaust air volume R = lC - 15
= Do.

Exhaust fan rotation speed (feedforward control) NR-KR
NRoX (ΔPR/ΔpRo)L 4 to 20 mA signal output where N is the design rotational speed OK of the electric motor of the exhaust fan 6, and KR indicates the exhaust air volume coefficient.

(5) For feedforward control of rise,
All parties feedback control the rotation speed of the exhaust fan 6 to see if the exhaust air volume Rm measured by the wind speed detector 20 matches the required exhaust air volume R.

(Required exhaust air volume) - (Measured exhaust air volume) ± (deviation) At that time, dead zones Ll and L2 are set around the required air volume. Then, the deviation e is calculated.

It is assumed that L, <e<Iv (required exhaust air volume) to (measured exhaust air volume), and feedback control is stopped to maintain the following rotation speed.

NR= KRNRoX (△PR/△PR8)2e<L
When l, NR-KR is 114Ro (e/Ro) and 2×kN. (e, /R,) = 14- L2 (When e, NR' = NR- +NR, (e/"o) + 2X-1'
NRo(ei/"o)-1 (6) Corrections are made at each control time until the deviation value falls within a predetermined dead zone. This makes it possible to suppress a decrease in air volume due to filter clogging.

(7) After completing the operation in (5) above, monitor the usage status of the draft chamber and if there is any change, Q-QB
+j qI X &, +Q.

By calculating R=e, RB+ΣQ,+, Xa1, the air volume is controlled, and the process returns to step (2).

As described above, when the power-saving control equipment for room-to-room differential pressure ventilation of the present invention is operated, it is possible to operate the room where there is a forced exhaust draft chamber whose usage conditions change and where high airtight performance is required to be maintained. can be maintained at a constant set differential pressure, preventing cross-contamination between rooms, and preventing a decrease in air volume due to changes in pressure loss over time in the duct system where the filter is located, while at the same time reducing the power of the exhaust fan to the minimum necessary. consumption can be limited to . In addition, even when the air supply is stopped for reasons such as cleaning, the differential pressure in the space is always maintained constant, eliminating the risk of cross-contamination. and ventilation power saving control can be implemented automatically.

[Brief explanation of the drawing]

Fig. 1 is an equipment layout system diagram showing an embodiment of the power-saving control equipment for room differential pressure ventilation of the present invention, and Figs. This is a flowchart showing calculation examples, and Figures 2 and 3 are the main program, Figure 4 is the subprogram of the air volume correction coefficient,
FIG. 5 shows a subprogram for carbon dioxide concentration sampling and averaging, and FIG. 6 shows a subprogram for four types of rotation speed calculations. 1... Highly airtight room, 2... Draft chamber 5
... Exhaust fan, 4... Exhaust duct, 5... On-off damper, 6... Draft chamber usage state detection sensor, 7... Air supply duct, 8... Differential pressure adjustment damper, 9 ...Differential pressure detection sensor, 10...Efuuki, 11
...Microcomputer, 17...+) Leh board,
18...Inverter unit. Applicant Takasago Thermal Engineering Co., Ltd. 17-149 JP-A-59-176530 (9) Value AP Tomomi 4) 2-So Procedure Amendment 0. May 41, 1982 1. Indication of the case Patent Application No. 50447 of 1988 2 Title of the invention Low differential pressure ventilation between rooms Power saving control equipment 3 Person making the amendment Relationship to the case Name of patent applicant (li) Representative of Takasago Thermal Engineering Co., Ltd.
View - Part 4 Agent 〒162 Brief description of the drawings in the specification, drawing 6, contents of amendments (1) Figures 2 to 4 in the bottom two lines of page 9 of the specification
~5 Corrected to Figure J. (2) "Figures 2 to 6 on page 16 of the specification, lines 11 to 18 are all Zabu programs.
FIG. 5 is a series of 70-charts showing examples of calculations performed by a microcomputer when controlling the equipment of the present invention. Correct to J. (3) Figures 2 to 6 of the drawings are deleted and the attached figures 2 to 5 are added. -159- gM*-T, (s)/T, (2)

Claims (1)

[Claims] One or more draft chambers 2 in one chamber 1
, and maintains the differential pressure between the chamber 1 and the outside at a constant level regardless of whether or not the draft chamber 2 is used, and at the same time controls the exhaust capacity of the exhaust fan 5 according to the usage status of the draft chamber 2. An on-off damper 5 is interposed in the exhaust duct 4 of each draft chamber 2, and the on-off damper 5 is operated to open and close based on a signal from a sensor 6 that detects whether each draft chamber 2 is used. A differential pressure adjusting damper 8 is interposed in the air supply duct 7 to the air supply duct 1, and the opening degree of the differential pressure adjusting damper 8 is controlled based on a signal from a differential pressure detection sensor 9 that detects the differential pressure between indoor and outdoor. Variable air volume blowers are used as the wind fan 3 and the fan 10, and the exhaust fan 5
In addition, a microcomputer 11 is attached to control the air volume of the air blower 10 based on the usage status of each draft chamber 2, pressure loss changes over time in the air supply and exhaust system, and the differential pressure between indoors and outdoors. Power saving control equipment.