Hydrogen production plant by water electrolysis

The invention can be used in the chemical industry and in the manufacture of stationary and transport fuel sources. Iron oxide is reduced by thermolysis when heated with an inert gas to produce oxygen at temperatures above 1200°C and pressure above 0.1 MPa. The iron is then oxidized by a stream of water vapor heated by an inert gas in a container alternately filled with heated inert gas and water vapor. By adsorption, or membrane, or electrochemical separation, hydrogen is separated as the final product from a stream of water vapor, as well as oxygen from a stream of inert gas. The cycle of oxidation and reduction of iron oxide is carried out in parallel switchable sections connected by inert gas and water vapor. 8 salary f-ly, 1 ill.

Hydrogen production. Hydrogen production (production) installations.

Introduction

The indoor hydrogen production unit is a comprehensive hydrogen production unit with a hydrogen production capacity of 30 nm³/h at a purity of 99.998% and a pressure of 10 barg. The
unit is fully automated, which significantly reduces the operator presence (maintenance) time. The installation is designed for completely continuous operation, the hydrogen flow rate at the outlet is automatically adjusted to the user's requirements. Thanks to the careful selection of the main components used, maintenance requirements are kept to a minimum.

Reliability

Special efforts have been made to ensure the highest level of security for our customers:

The protocol ensures safe shutdown in the event of a failure in the control system (PLC)
Continuous Atmospheric Hydrogen Detection (HTA) System
Reliable logic circuit for all parameters (more than 30 parameters are monitored)
Uninterruptible Power Supply (UPS) provides shutdown in case of power failure
Continuous gas purity monitoring (HTO)
An inherently reliable design (passive safety), which allows the installation to perform an emergency mechanical pressure release in the event of failure of the controls.
Minimal presence of gas in the system (only a few Nm³/h at full production)
Multiple redundancy for critical reliability parameters. In addition to the standard transmitters, each safety parameter is also monitored by a safety relay, which triggers an alarm or stops the unit in the event of a disturbance in normal operation (e.g. electrolyte level, cell pack temperature, system pressure, ...).

Automation

The hydrogen production plant is carefully designed to operate continuously with minimal human intervention required while maintaining reliability levels in accordance with the most stringent industry standards.

The plant starts and maintains hydrogen production fully automatically, while key safety and production parameters are continuously checked at the same time. The following features are included as standard in our installation:

Hydrogen pressure control:
The HMI (Human Machine Interface) on the control panel allows the operator to select the required gas pressure (between 6 and 10 barg). The unit automatically adjusts the performance coefficient to maintain the set pressure (optionally a pressure reduction valve can be added to meet customer requirements).
Hydrogen Flow Control:
Based on pressure, hydrogen production and consequently hydrogen output is constantly adjusted within operating limits to follow actual demand. Hydrogen will be (partially) released into the atmosphere for a maximum of 20 minutes if the demand is below the minimum plant capacity.
Automation of cooling:
The flow of cooling water entering the heat exchangers is constantly regulated by PLC (thermostat control). This function ensures a constant operating temperature for the electrolysis process.
Remote I/O
: Using a modern connection, we have significantly reduced the number of connecting cables and therefore the time required for installation. The implementation of puncture in combination with a safe PLC and safe I/O allows the system to fully comply with the most stringent current regulations and safety standards. The PLC automatically diagnoses any communication errors, not only making the system safer, but also reducing troubleshooting time and effort.
Semi-automatic nitrogen purging:
Nitrogen purging is necessary before starting the unit when the internal pressure is below 15 kPa. The system's PLC sequentially activates the various valves in the system, thus ensuring that all air is evacuated before hydrogen production. The only manual action required is to change the position of the two valves. This action can be optionally automated so that this action is performed by a remote operator.

Installation control and monitoring

Features of the advanced control panel and monitoring capabilities:

Remote Monitoring:
Allows the operator to access the HMI screen located on the control panel and operate the electrolyser from a remote connection. It displays process parameters, dynamics, events, alarms, and allows the operator to enable/disable individual element packages.
Key Switch:
Allows the operator to start/stop the unit. For safety reasons, to start the installation, it is necessary that both the internal and external switches with the key are in the START position.
Reset Button:
Resets the safety circuit after tripping. Once the reset button is pressed, the unit enters production fully automatically after completing the safety initialization procedure.
Emergency Shutdown:
When this button is pressed, the system immediately turns off power to cell packages and auxiliary support systems and relieves system pressure. Due to this, the system will be switched to safe mode to avoid an emergency.
Touch Screen Human Machine Interface (HMI)
: The HMI screen is located on the control panel and allows the operator to monitor and operate the electrolyser either from the screen or from a remote connection. The monitoring system includes data recording on a compact flash card. It also allows our technicians connect to the electrolyser to diagnose and correct fault cases and alarms if necessary. The PLC uses Siemens S-7 software.

Scope of delivery

Basic equipment
Technology discount

The key component of the electrolysis skid is a package of bipolar cells for electrolysis of water under pressure. The cell stack consists of annular electrolysis cells, each containing two electrodes and one alkaline inorganic ion exchange membrane.

Generation of H2 and O2 occurs when current is applied to a stack of cells. The gases are then directed to a gas separator, which is a double stainless steel pressure vessel, after which they are washed in a specially designed pressure vessel located above the gas separator.

The equipment of the technological part is made of high quality materials and complies with ATEX directives.

This equipment is intended for indoor installation only. Please note that the hydrogen production part is classified for Zone II use only. However, if the process part is protected by an optional ATEX enclosure, these Zone II requirements can be ignored. In this case, the installation location is required to be “general purpose”.

The technological part is supplied as a fully assembled skid, which includes equipment, for example:

Cell Packs
Gas separators, hydrogen gas scrubbing unit and coalescing filters
Heat exchangers for electrolyte and gas cooling systems
Leak detector tray with level switch
Hydrogen Detector (HTA), Hydrogen in Oxygen (HTO) Analyzer Panel
Bale devices and distribution boxes: sensors, transmitters, relays, etc.
Valves and vent manifolds (H2 and O2)

Control Panel

The control panel cabinet includes a PLC and all related equipment to ensure automatic and reliable operation of the plant. The control panel will be connected via cables to both the process part and the power rack. Characteristics:

Approved electrical enclosure with 2 lockable doors
Cooling fans + air filtration system
PLC (Siemens S-7 software)
External: terminal with display for visualization and HMI
Emergency stop on the housing door
Uninterruptible power supply for safe shutdown
24 V DC current power supply
Circuit breakers and transformers
Printed Circuit Boards and Sound Alarms

Power rack

The power rack converts the incoming 3-phase AC power into the stabilized DC current required for the electrolysis process. It includes:

Cover with lockable door
Cooling fans + air filtration system
Door switch safety interlock
Transformer
Rectifier
Circuit breakers, starters, thyristors and bridge rectifiers
Measuring cell packages with an ammeter and a voltmeter on the door
Phase checking device

Hydrogen purification system

The hydrogen purification system is designed to further purify hydrogen to a minimum level of 99.998%. This purity is achieved in 2 stages:

Step 1: To reduce the O2 content in the H2 gas stream using a catalytic reaction. The yield of O2 to H2 is less than 10 ppm or optionally less than 2 ppm.

Data sheet

Output	H2 production	Consumption	12 to 30 Nm³/h
		Purity (before hydrogen purification system)	99.9% (*H2O saturated) O2 < 1.000 ppm
		Purity (after hydrogen purification system)	99.998%; 02 < 2 ppm; N2; 12 ppm Atmospheric dew point: -60°C (-75°C with improved purity) CO+CO2+THC < 70 ppb
		Operating pressure at full flow	10 barg (after hydrogen purification system)
		Number of element packs	2
	O2 production**	Nominal flow	resettable
Power	Power requirements	Calculation of power consumption at full flow without auxiliary support systems	5.0 kW/Nm³
		Voltage	3 x 400 VAC ± 10% 3 x 480 VAC ± 10% (standard in US option) 3 x 575 VAC ± 10% (standard in CA option)
		Frequency	50 Hz ± 3% 60 Hz ± 3% (standard in US and CA options)
		Installed power	1 x 240 kVA
Support systems	Nitrogen for purge	Pressure	4 to 10 barg
	Nitrogen for purge	Quantity per blowdown	approx. 2 nm³
	Cooling water	Electrolyte cooling circuit ***	Provided by closed loop cooling system If not included: - max. water temperature: 40°C – max. flow rate: 4 m³/h
	Cooling water	Gas cooling circuit	Provided by chiller If not included: - water at 15°C - max. flow rate 0.2 m³/h
	Feed water	Deminer consumption. water in process process	< 1 l/Nm³ H2
		Consumption of tap water in a reverse osmosis installation ***	1.5 – 2 l/Nm³ H2 (depending on the quality of tap water)
		Pressure	2 to 4 barg
	Air instrumentation	Min. pressure	6 bar (air compressor as option)
	Air instrumentation	Consumption (without control valves)	± 80l/min (not constant consumption)
First filling	Electrolyte	Type	H2O + 30% wt. KOH
First filling	Electrolyte	Quantity	approx. 500 l.
Installation	Environmental conditions environment	Ambient temperature range environment	+5°C to +40°C
		Max. temperature for 100% output parameters	+40°C
		Installation area *****	indoors, general purpose area
		Relative humidity	< 95%
		High mark	< 500 m

The above data is provided for information only and is subject to change without notice. Technical data cannot be used for warranty purposes.

(**) Oxygen use requires the optional "oxygen use" feature (***) Only applicable if the "closed circuit cooling" option is not selected. (****) Based on the fact that the reverse osmosis feedwater treatment system is included in the scope of supply. (*****) The process part must be equipped with an optional ATEX enclosure (ATEX zone II without enclosure).

Dimensions:

Technological part Empty weight ~2450 kg Operating weight ~ 2900 kg

Power rack Total weight ~1500 kg Total weight ~450 kg	Hydrogen purification system Weight ~600 kg	Control panel Dimensions: ~ 900x900x2300 mm Dimensions: ~ 1000x1000x2000 mm

Additional (technological) options on request:

Purity Improvement -75 °C 2ppm
O2
This option reduces the atmospheric dew point of produced H2 from -60 °C to -75 °C and the O2 content of produced H2 from 10ppm to 2 ppm.

Reduced N2 content - atomizing sprinkler

An atomizer is a device installed at the demineralized water inlet of a hydrogen production plant to reduce the N2 content to less than 2 ppm of H2 produced. This will allow us to achieve 99.999% hydrogen purity.

Real-time cleanliness measurement

The H2 produced is continuously monitored in real time, both in terms of water content (“dew point”) and oxygen content. This option can only be selected in combination with a hydrogen purification system.

Drain valve (only in combination with real-time cleanliness measurement system)

This device automatically releases H2 into the atmosphere if its quality does not meet specifications. This option can only be selected in combination with the H2 real-time purity measurement system.

Oxygen use

As a standard, O2 is released into the atmosphere. The manufacturer can provide an optional system for purifying O2 and preparing it for further use/purification by the customer.

Air conditioning system on the control panel

This is a modular air conditioning unit installed on electrical panels. This device is recommended for systems frequently operated at ambient temperatures. environments more than +40 °C, but below 45 °C

Mass flow meter

A mass flow meter is a direct measurement of the volume of H2 flowing into the customer's line.

Oxygen content in the atmosphere detector

An atmospheric oxygen transmitter can be implemented in a process room to continuously monitor the O2 level in the process room atmosphere. The alarm system sounds if oxygen levels fall below or rise above safe limits.

Back pressure regulator

Guarantees the performance of the installation by maintaining the generator and deoxo dryer at a stable pressure. Fluctuations in the customer's line will not affect the pressure in the process part (will be added to the installation if directly connected to the compressor).

Instrument air compressor:

Compact yet reliable bale air compressor for general purpose installation to eliminate the need for external bale air supply.

Direct connection to renewable energy sources:

We can offer tailored approaches to directly connect an electrolyser to renewable energy resources (eg power-controlled electrolyser), providing an efficient, high-performance system optimized for a specific application.

Automatic restart

This function allows the installation to continuously determine the current pressure in the customer's line. If the installation is in standby mode, this function can be used to automatically restart the installation as soon as the customer's line pressure falls below a preset threshold.

Automatic N2 purge:

Allows the entire sequence of N2 purge and hydrogen purification system to be carried out automatically. Nitrogen purging is required before starting the unit if the internal pressure is below 15 kPa. The system's PLC activates the various valves in the system in stages, ensuring that all air is removed before hydrogen production begins.

Contents:

Electrolyzer – 1 pc.
Package of elements 15 nm3/h – 2 pcs.
Control panel with monitoring system – 1 pc.
Power rack - 1 pc.
Connecting cable – 1 pc.
Hydrogen purification system - 1 pc.
Quality control of incoming demineralized water
Chiller for gas cooling – 1 pc.
Closed loop cooling system – 1 pc.
Atmospheric Hydrogen Detection System (HTA) – 1 pc.
Feed water preparation system – 1 pc.
Water tank with a volume of 20 m3 – 1 pc.
Spare parts
Consumables for 1 year
Standard tool kit
Commissioning works

Electrolysis of water in industrial hydrogen generators

Electrolysis

This is a redox reaction that occurs only under the influence of electricity. In industrial hydrogen generators, water is electrolyzed to produce hydrogen and oxygen. For the reaction to occur, two electrodes must be placed in the electrolyte, connected to a DC power source:

Anode
is the electrode to which the positive conductor is connected;
Cathode
is the electrode to which the negative conductor is connected.

Below is a schematic diagram of an industrial alkaline electrolyzer.

Electrolysis of water

Under the influence of an electric current, water is divided into its constituent molecules: hydrogen and oxygen. The negatively charged cathode attracts hydrogen cations, and the positively charged anode attracts OH - anions.

Demineralized water used in industrial electrolysis plants is itself a weak electrolyte, so strong electrolytes are added to it to increase the conductivity of electrical current. Electrolytes with a lower cation potential are often chosen to eliminate competition with hydrogen cations: KOH or NaOH. The electrochemical reaction occurring at the electrodes is as follows:

Reaction at the anode: 2H2 O → O 2
+ 4H + + 4e − - release of oxygen;
Reaction at the cathode: 2H2O + 2e − → H 2
+ 2OH − - hydrogen evolution.

An industrial electrolyzer is assembled according to a bipolar circuit, where bipolar “intermediate” electrodes with different charges on the sides are placed between the main electrode and the cathode. On the side of the main anode, the intermediate electrode has a cathode side, on the cathode side - an anode side (see figure).

Next, in order to obtain pure hydrogen and oxygen, it is necessary to separate the gases formed at the electrodes, and for this, separation ion exchange membranes are used (see figure). The amount of hydrogen produced is twice as much as the oxygen produced and therefore the pressure in the hydrogen cavity rises twice as fast. To equalize the pressure in the cavities, a pressure equalizing membrane is used at the outlet of the electrolyzer, which prevents the transfer of hydrogen into the oxygen cavity through channels intended for circulation of the electrolyte.

This method is the most used method in industry and makes it possible to produce hydrogen gas with an efficiency of 50 to 70% with a productivity of up to 500 m 3 /hour with specific energy consumption of 4.5-5.5 N2m 3 /kWh.

ELECTROLYSIS ON TPE

At the moment, the most effective separation method is electrolysis using solid polymer electrolytes based on a perfluorinated ion exchange membrane.

This type of electrolyzer allows producing hydrogen with an efficiency of up to 90% and is the most environmentally friendly. Electrolyzers with TPE are 6-7 times more expensive than alkaline ones and therefore have not yet become widespread in industry.

source

Ambient conditions environment	Ambient temperature range environment	20°C to +40°C
	Temperature, coolant output water	ambient temperature environment + 3°C
	Max. ambient temperature environment for 100% yield	+40°C
	Noise level at 10m from the fan	less than 69 dBa
Installation	Dimensions (LxWxH), m	2.7 x 1.5 x 1.7
Installation	Empty weight	322 kg.

Tap water consumption	1.5 – 2 l/nm³ hydrogen (H2)	Ba2+	0.05 mg/l max.
Temperature	10°C – 30°C	Ca2+	20-50 mg/l max.
Pressure	2-4 barg	Mg2+	10-30 mg/l max.
There is no microbiological contamination	—	Cl-	150 mg/l max.
Langelier index	2.5 max.	SO42-	150 mg/l max.
pH	7,0-8,5	HCO3-	100 mg/l max.
Free chlorine	0.02 mg/l max.	Fe (general)	0.5 mg/l max.
Suspended solids	0.05 mg/l max.	Al (general)	0.05 mg/l max.
CO32-	0.5 mg/l max.	Electrical conductivity	1000µS/cm max.
Turbidity	NTU < 0.5	SiO2	0.5 mg/l max.
Na+	200 m g/l max.	Manganese	0.05 mg/l max.
K+	50 mg/l max.

Environmental conditions	Ambient temperature range environment	+5 to +45°C
Environmental conditions	Temperature, cool water	+15°C
Installation	Dimensions (HxWxD), m	1.35 x 0.88 x 0.8
Installation	Empty weight	185 kg.