JP2013083418A - Inverter control of closed drain pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of losing a large quantity of energy, by discharging flash steam in the atmosphere when a drain is too much, without fitting the drain supply timing, since a water supply frequency is many when a possessing water quantity of a boiler is little, in a closed drain collection in multi-can installation of a once-through boiler.SOLUTION: The drain can be supplied to the boiler by 100% by controlling a drain pump in multistage by an inverter in response to a water supply request of a plurality or boilers. Alternatively, there is no loss in the flash steam by using the high pressure drain side flash steam in a low pressure steam line.

Description

The present invention relates to an apparatus for recovering heat to a boiler while maintaining a certain pressure on steam drain.

A type of steam drain recovery device that is used as a closed drain recovery device.

Problems to be solved by the invention

When installing multiple cans of once-through boilers, because the amount of water held by the boiler is small, water supply requests frequently occur from each boiler, so the discharge pressure of the drain pump that supplies the drain fluctuates and exceeds the pressure resistance of the pump casing There is. In addition, the drain pump starts and stops frequently, and a large force is applied to the shaft and blades of the pump, greatly affecting the life of the drain pump.

Means for solving the problem

The drain pump is controlled in multiple stages by an inverter according to the water supply requirements of each boiler. Further, when there is no water supply request from the boiler, it is kept waiting at a reduced speed.

Effect of the invention

The fluctuation range of the pump discharge pressure is suppressed, and the influence on the shaft at the time of starting the drain pump is reduced. In addition, the rotational speed of the pump power can be kept appropriate, and power can be saved.

The flow which shows embodiment of this invention. The flow of the usage example of this invention in a cardboard factory.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.

In FIG. 1, (a) is a tank for storing drain, [PS-1] pressure sensor, (1), (2), (4) solenoid valve, (9) safety valve, [BS] Electrode holder. C-1 Check valve prevents back flow.

(B) is a drain pump, which is controlled by a control panel (c) and an inverter (d). The needle valve of (7) prevents the pump from being cut off.

(E) Consists of a solenoid valve (3) for supplying drain to the boiler, a check valve C-2, and [BSH] and [BSL] for controlling the solenoid valve.

Each part is connected by piping.

The operation of the above configuration will be described below. ▲ e ▼ Steam generated from boiler is 1. It is sent to the load device via the pipe. Steam is drained by the load device. It accumulates in the tank ▲ a ▼ through the pipe. (A) The tank is sensed by the [PS-1] sensor, and (1) and (2) the electromagnetic valve is opened and closed to exhaust the flash vapor and maintained at an arbitrary pressure.

▲ a ▼ The drain of the tank is 5. 5. It is supplied to the (b) drain pump through the pipe and pressurized by the (b) drain pump. Piping, (3) Solenoid valve, C-2 check valve, 7. It passes through the pipe and is supplied to the boiler.

(7) Adjust the needle valve. (B) Prevent the drain pump from shutting down.

(3) The solenoid valve is opened at (e) below the boiler water level [BSH] and (e) is supplied to the boiler.

(A) When the water level of the tank reaches H of the [BS] electrode holder, (4) Open the solenoid valve and (a) discharge the tank outside.

(B) The drain pump controls the output with an inverter. ▲ a ▼ The operation is stopped below the tank [BS] electrode holder LL. The output of the inverter is changed stepwise in accordance with the number of open (3) solenoid valves of a plurality of (e) boilers above the electrode holder L. This control reduces the weight applied to the shaft of the pump when the drain pump is started, and prevents a pressure higher than the pressure resistance from being applied to the drain pump casing.

[FIG. 2] shows a closed drain recovery device in a corrugated board production process and a system for reusing the steam drain flush steam as a low pressure steam for a hot plate.

The operation will be described below. ▲ e ▼ The steam generated in the boiler is 1. It flows through the pipe and supplies heat to the ▲ h ▼ roll and ▲ g ▼ hot plate of the corrugating machine. The supply pressure of the steam is divided into two systems: (g) hot plate g-1, g-2, (h) high pressure side of the roll and (g) low pressure side of hot plate g-3. The steam on the high-pressure side is radiated by the (g) hot plate g-1, g-2, and (h) rolls, becomes drained, and is discharged from the trap of (T) -1. Drain It accumulates in the flash tank of (i) through this pipe.

The pressure of the flash tank of (i) is detected by the pressure sensor of [PS-2], and the electromagnetic valve of (5) and (6) is controlled to arbitrarily maintain the pressure of the flash tank of (i). The flash steam discharged from the solenoid valves (5) and (6) is 15.2. It flows to the drain tank through the pipe.

The drain of the flash tank of (i) is discharged by the low pressure multi-capacity trap of (T) -3. 15.2. It accumulates in tank ▲ a ▼ through the pipe.

The flash steam generated in the flash tank of (i) is 14. The pressure is controlled by the pressure reducing valve {circle around (10)} through the pipe and supplied to the hot plate g-3. The heat is released by the hot plate g-3 to be drained and discharged from the trap at {t} -2.

The drain of the hot plate g-3 is 16.2. It accumulates in the tank through the pipe. (A) The drain accumulated in the tank is pressurized by the (b) drain pump and supplied to the boiler (e).

(A) When the water level of the drain of the tank reaches H of the [BS] electrode holder, (4) The solenoid valve opens 10.12. Discharge to the boiler water tank through the pipe.

(A) Flash steam discharged from (1) and (2) solenoid valves to control the tank pressure is used for heating (j) boiler feed water tank. Install a silencer to mute the sound. [8] Control the solenoid valve with the temperature sensor (8), and (j) keep the boiler feed tank temperature below the upper limit.

[Figure 2] shows the flow of steam and drain during the corrugated board production process. This is an example where the drain is reused all the time.

A large amount of high-pressure steam is used in the production process of the cardboard factory. The drain rate is 100%, and nearly 26% of the total heat of steam is exhaust heat. Drain recovery equipment is provided, but a large amount of flash steam is discharged, and energy is wasted. If we can establish a system for 100% effective reuse of drainage, it will greatly contribute to the reduction of fuel and CO2.

Symbol Name Symbol Name ▲ a ▼ Drain tank ▲ 1 Solenoid valve ▲ b ▼ Drain pump ▲ 2 ▼ Solenoid valve ▲ c ▼ Control panel ▲ 3 Solenoid valve ▲ d ▼ Inverter ▲ 4 ▼ Solenoid valve ▲ e ▼ Through-flow boiler ▲ 5 ▼ Solenoid valve ▲ f ▼ Steam header ▲ 6 ▼ Solenoid valve ▲ g ▼ Heat plate ▲ 7 ▼ Needle valve g-1 Heat plate 1 group ▲ 8 ▼ Solenoid valve g-2 Heat plate 2 group ▲ 9 ▼ Safety valve g-3 Heat Plate 3 group ▲ 10 ▼ Silencer ▲ h ▼ Roll ▲ 11 ▼ Pressure reducing valve (high pressure side)
▲ i ▼ Flash tank ▲ 12 ▼ Pressure reducing valve (low pressure side)
▲ j ▼ Water supply tank ▲ T ▼ -1 Steam trap (high pressure)
[BS] Electrode holder (drain tank) ▲ T ▼ -2 Steam trap (low pressure)
[BSH] Electrode holder (Boiler H) ▲ T ▼ -3 Steam trap (Low pressure, large capacity)
[BSL] Electrode holder (Boiler L) [PS-1] Pressure sensor (Drain tank)
C-1 Check valve [PS-2] Pressure sensor (flash tank)
C-2 Check valve [TS] Temperature sensor (side temperature resistor)
C-3 Check valve C-4 Check valve [PM] Boiler feed pump

Claims (2)

The [b] drain pump described in [0017] controls the output with an inverter. ▲ a ▼ The operation is stopped below the tank [BS] electrode holder LL. The output of the inverter is changed stepwise in accordance with the number of open (3) solenoid valves of a plurality of (e) boilers above the electrode holder L. By this control, a mechanism that reduces the excess load applied to the pump shaft when starting the drain pump and prevents the pressure of the drain pump casing from being overpressured. [0020] [0021] The pressure of the flash tank (i) described in [0022] is detected by the pressure sensor (PS-2), and the solenoid valves (5) and (6) are controlled. Hold the pressure of the flash tank arbitrarily. The flash steam discharged from the solenoid valves (5) and (6) is 15.2. It flows to the drain tank through the pipe. The drain of the flash tank of (i) is discharged by the low pressure multi-capacity trap of (T) -3. 15.2. It accumulates in tank ▲ a ▼ through the pipe. The flash steam generated in the flash tank of (i) is 14. The pressure is controlled by the pressure reducing valve (10) via the pipe, supplied to the hot plate g-3, and reused by the hot plate g-3. The flash vapor is drained by the hot plate g-3 and is discharged from the trap at (t) -2. A mechanism that effectively uses flash steam in the corrugated board production process.

Images