JPH0157242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam pressure control device for a boiler control device, and particularly to a device that can be suitably implemented in a steam generator such as a waste heat boiler whose heat source fluctuates widely.

In the case of waste heat boilers that use exhaust gas from metal smelting equipment as a heat source, the flow rate of the heat source varies greatly due to its nature. As a result, when using steam from a waste heat boiler for equipment that constantly uses steam at a predetermined pressure, such as a steam turbine, it is necessary to always supply steam at a constant pressure to the boiler, regardless of fluctuations in the heat source. . However, in the past, means for keeping the vapor pressure constant were not preferable to the point of view of heat recovery and utilization.

The purpose of the present invention is to eliminate the above-mentioned problems and provide a device that can maintain the pressure of steam generated by a boiler device with large heat source fluctuations almost constant and supply it to a turbine, etc., and can also supply water stably at all times. There is a particular thing.

In short, this invention branches the main steam pipe and main water supply pipe into pipes, and places an accumulator in the middle of the branched pipes to accumulate and release heat, thereby compensating for fluctuations in the heat source and keeping the steam pressure constant. In particular, the present invention relates to a device that can constantly and stably supply water.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In Figure 1, 1 is a waste heat boiler, 2
is a turbine operated by steam generated in this waste heat boiler 1. 3 is this waste heat boiler 1
A steam branch pipe 4 having a steam valve 5 branches off from the main steam pipe 3 . A steam flow rate transmitter 20a and a pressure detector 13 are provided on the downstream side of the steam branch branch of the main steam pipe 3. Of these, the steam flow rate transmitter 20a and the water level detector provided in the waste heat boiler 1 are two elements. It constitutes a type water level adjustment transmitter 20. Next, the steam branch pipe 4 is connected to a drain tank 8, and an accumulator 6 having a heat storage medium such as water inside is arranged in the middle thereof. One end of a main water supply pipe 7 is connected to the drain tank 8, and the other end of the main water supply pipe 7 is connected to the drum of the waste heat boiler 1. A water supply branch pipe 10 having a flow rate control valve 11 is branched on the downstream side of the water supply pump 9 installation part of the water supply main pipe 7, and the branched water supply branch pipe 10 is connected to the waste heat boiler 1 via the accumulator 6. Reference numeral 12 denotes a flow rate control valve provided in the main water supply pipe 7 on the downstream side of the water supply branch branch. A valve designated by the reference numeral 21 provided on the upstream side of the branch part of the water supply branch pipe 10 is a water supply flow rate control source valve that adjusts the flow rate of the entire water supply. Next, 15 is a control box (hereinafter simply referred to as "control box") which outputs a control signal by storing and comparing measured values, and includes the steam valve 5, the flow rate control valve 11, the flow rate control valve 12, the pressure detector 13, A two-element water level adjustment transmitter 20 and a water supply flow rate control source valve 21 are each connected to the control box 15.

In the above device, when the pressure detector 13 detects that the steam supplied to the turbine 2 maintains a predetermined pressure, the control box 15 closes the steam valve 5 of the steam branch pipe and restarts the waste heat boiler 1. Almost all of the generated steam is directly introduced into the turbine 2. Next, when the steam pressure rises, the control box 15 opens the steam valve 5 and adjusts its opening to allow excess steam to flow into the steam branch pipe 4 and reduce the pressure of the steam supplied to the turbine 2. Adjust to the specified value. The steam flowing into the steam branch pipe 4 reaches the accumulator 6, exchanges heat with the internal heat storage medium, radiates heat into the accumulator, and then condenses itself and reaches the drain tank 8. On the other hand, the feed water W is supplied to the waste heat boiler 1 via the main water supply pipe 7 and the water supply pump 9, but if the amount of exhaust gas passing through the waste heat boiler 1 is sufficient, the flow control valve 11 is almost closed, and the flow control valve 12 is closed. The main water supply pipe 7 is opened and the water supply W is introduced directly into the waste heat boiler 1 through the main water supply pipe 7. In this case, the flow control valve 11,
No. 12 has a minimum flow limit, and even when the valve is in the closed state, it is slightly opened so that the water supply can flow.When the valve is opened again, the water supply passes through, causing a thermal shock to the pipe in the flow path Make sure there are no. Next, if a drop in steam pressure is detected by the pressure detector 13, the control box 15 opens the flow rate control valve 11 to open part or all of the water supply W (in the case of all of the water, the flow rate control valve 12 is almost closed). is introduced into the water supply branch pipe 10. Water supply W in the water supply branch pipe 10
The steam flows through a pipe in the accumulator 6, exchanges heat with the heat storage medium that stores the heat of the steam, raises the temperature, and then is supplied to the waste heat boiler 1. This increases steam generation in the waste heat boiler 1 and maintains the steam pressure at a predetermined value. Of course, in this case, the steam valve 5 is kept closed. The control box 15 operates the flow rate control valve 11 and the flow rate control valve 12 according to the detection result by the pressure detector 13.
The opening degrees of the two are appropriately adjusted, for example, so that they are inversely proportional to each other, and the water supply W is distributed so that a predetermined steam pressure is obtained. In addition, all water supply is done using an accumulator 6.
Even when the flow rate control valve 12 is introduced into the flow rate control valve 12, a minimum flow state is ensured on the downstream side of the flow rate control valve 12 for the same reason as described above.

While the above operations are being performed, the control box 15 further receives a water level signal in the waste heat boiler 1 from the two-element type water level adjustment transmitter 20, and adjusts the opening degree of the water supply valve 21. This adjusts the total water supply amount in the waste heat boiler 1 and controls the boiler water level to always be at an appropriate value. The water supply flow rate control source valve 21 is connected to the water supply branch pipe 1
Since the branch point 0 is located on the upstream side, the total amount of water supply is controlled, but by changing the opening degree of the water supply flow rate control source valve 21, the distribution ratio of water supply to the accumulator 6 and water supply directly to the waste heat boiler 1 can be adjusted. It will never be changed.

By implementing this invention, steam at a predetermined pressure can always be obtained regardless of fluctuations in the heat source of the boiler. By controlling the water supply flow rate control valve, the total amount of water supply can be controlled according to the turbine bin load. Therefore, the boiler can always be supplied with an appropriate amount of water, the boiler can always function normally, and the load on the turbine can be coped with, among other effects.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an apparatus according to the present invention. 1...Waste heat boiler, 3...Main steam pipe, 4...Steam branch pipe, 6...Accumulator, 7...Main water supply pipe, 10...Water supply branch pipe, 11, 12...Flow rate control valve, 15...Control Box, 20... Two-element type water level adjustment transmitter, 21... Water supply flow rate control source valve.

Claims (1)

[Scope of Claims] 1. An accumulator is arranged between a steam branch pipe branched from a main steam pipe and a water supply branch pipe branched from a main water supply pipe connected to a steam generator such as a waste heat boiler,
In a system that maintains the steam pressure of the main steam pipe almost constant at all times by appropriately switching between heat storage and heat radiation in the accumulator by operating the flow rate control valves of the steam branch pipe, water supply branch pipe, and main water supply pipe, the water supply flow rate is adjusted to the main water supply pipe on the upstream side of the branch point of the water supply branch pipe. A boiler control device characterized in that a control source valve is provided, and a water level transmitter is provided in a steam generator. 2. The steam branch pipe, the water supply branch pipe, the water supply main pipe flow rate control valves, the water supply flow rate control source valve, and the water level transmitter are connected to a control box that emits a control signal based on a comparison of stored and measured values. Boiler control device according to scope 1. 3. The boiler control device according to claim 1 or 2, wherein the flow rate control valves provided in the main water supply pipe and the branch water supply pipe have a minimum flow rate restriction. 4. The boiler control device according to claim 1 or 2, wherein the water level transmitter is a two-element water level adjustment transmitter.